Cationic materials and formulations for drug delivery

ABSTRACT

Cationic polymers are provided for delivering anionic active agents, preferably in the form or nanoparticles and other nanostructures. The polymer can be a polycation homopolymer or a copolymer containing a polycation block. The polycations and polycation containing polymers can contain dicarboxylic acid ester units and units of (α-amino acid)-α,ω-alkylene diester units. The nanoparticles can contain high loadings of anionic active agents, with sustained release of the active agents. Methods of making the polycations and polycation containing polymers are provided. Methods of making the nanoparticles and formulating them for administration to an individual in need thereof are also provided.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant numberCA151884 and grant number EB015419-01 awarded by the National Institutesof Health. The government has certain rights in the invention.

FIELD OF THE INVENTION

This invention is generally in the field of materials for pharmaceuticalapplications.

BACKGROUND OF THE INVENTION

The delivery of any therapeutic compound to an individual or a patientin need thereof may be impeded by any one or several factors such aslimited ability of the compound to reach a target cell or tissue, or byrestricted entry or trafficking of the compound within cells. Variousdelivery vectors have been developed to encapsulate and deliver manyclasses of drugs and have proven a promising strategy to effectivelytreat cancers, diabetes, cardiovascular diseases, and many otherdisorders. For anionic drugs, such as proteins and nucleic acids, safeand effective delivery to the desired disease locations or intracellularsites remains a major challenge. This is, at least in part, due to theintrinsic properties of these drugs. Most proteins have high molecularweight (MW), surface charges, and/or vulnerable tertiary structures (Guet al, Chem. Soc. Rev. 2011, 40:3638). Nucleic acids have the similarissues. Many nucleic acids are stable for only limited times in cells orplasma. Nucleic acid drugs should usually be delivered into thecorresponding intracellular target site, i.e. the nucleus or cytosol.Specific and robust delivery vehicles are needed to facilitate loading,delivery, and controlled release of anionic drugs, especially forproteins and nucleic acids.

Numerous platforms have been developed as carriers of anionic proteins,and nucleic acids. Microspheres (Langer et al, Nature 1976, 263: 797;Kang et al, J. Controlled Rel. 2012, 160: 440) and hydrogels (Vermondenet al, Chem. Rev. 2012, 112: 2853; Peppas et al, K, Expert Opinion onBiological Therapy 2004, 4: 881) have been utilized to solve thesustained protein and nucleic acid release issue. These systems havelimited applications for intracellular protein and nucleic acid deliverydue to their large size. Platforms such as liposomes (Swaminathan et al,Expert Opinion on Drug Delivery 2012, 9:1489; Yan et al, Polymer Reviews2007, 47:329.), conjugates (Duncan et al, Journal of Drug Targeting2006, 14:337; Duncan, Nat Rev Drug Discov 2003, 2:347), nanotubes(Brahmachari et al, Angewandte Chemie International Edition 2011,50:11243), and polymeric nanoparticles (Kamaly et al, PNAS 2013,110:6506; Rana et al, Current Opinion in Chemical Biology 2010, 14:828)are being extensively investigated for effective intracellular delivery.These platforms often suffer from low loading of the negatively chargeddrug and release profiles characterized by a large initial burstrelease.

The anionic proteins, anionic protein analogues and nucleic acids arenegatively charged and have complicated, sensitive, and fragile 3-Dstructure with nm scale sizes. There remains a need for materials andmethods to load and encapsulate proteins and nucleic acids with highefficiency and high loading, and release them in a sustained mannerwhile maintaining their bioactivity.

It is therefore an object of the invention to provide improvedmaterials, compositions, and formulations for drug delivery, especiallyof negatively charged drugs such as proteins and nucleic acids.

It is an additional object of the invention to provide compositions withhigh loading efficiency of negatively charged drugs such as proteins andnucleic acids.

It is also an object of the invention to provide compositions withsustained release of active agents, including sustained release ofnegatively charged drugs such as proteins and nucleic acids.

It is a further object of the invention to provide methods of makingimproved materials, compositions, and formulations for drug delivery,especially of negatively charged drugs such as proteins and nucleicacids.

It is additionally an object of the invention to provide methods ofusing the materials, compositions, and formulations to deliverynegatively charged drugs to a patient in need thereof.

SUMMARY OF THE INVENTION

Cationic polymers are provided for drug delivery. The cationic polymerscan be used for delivering anionic active agents, preferably in the formof nanoparticles and other nanostructures. In some embodiments thenanoparticles and nanostructures have high loading efficiencies, evenfor anionic active agents such as nucleic acids and negatively chargedproteins. Methods of making the polymers, nanoparticles containing thepolymers, and pharmaceutical formulations thereof are also provided.Methods of using the nanoparticles and the pharmaceutical formulationsdrug delivery, including for the delivery of anionic active agents to apatient in need thereof are also provided. The delivery systems allowsco-loading and delivery of multiple drugs, and, responsive release atdesired time points or sites.

The polymer can be a polycation homopolymer or a copolymer containing apolycation block. In some embodiments the polycation is positivelycharged in neutral, acidic, and most basic pH environments. The polymercan be a block copolymer such as a di-block, tri-block or othermulti-block copolymer including a polycation block with additionalpolymer blocks that can include hydrophilic polymers, hydrophobicpolymers, biodegradable polymers, or a combination thereof. The blockcopolymer can be an amphiphilic polymer. The polycation or polycationcontaining copolymer can be a low molecular weight polymer, e.g. havinga molecular weight between 100 Da 10 kDa or between 1.0 kDa and 10.0kDa, or can be a high molecular weight polymer, e.g. having a molecularweight between 40 kDa and 60 kDa or between 40 kDa and 1,000 kDa.

The polycations and polycation containing polymers provided can containdicarboxylic acid ester units and units of (α-amino acid)-α,ω-alkylenediester units. The (α-amino acid)-α,ω-alkylene diester units can includecationic amino acids such as lysine, arginine and histidine. Thedicaroboxylic acid ester can include dicaroboxylic acids of linear andbranched alkyl and substituted alkyl, alkenyl, or alkylene oxidecontaining from 2 to 20 carbon atoms. The polycation can contain unitshaving the structure

where the R₁ groups include linear and branched alkyl and substitutedalkyl, alkenyl, or alkylene oxide containing from 2 to 20 carbon atoms;at least one R₂ is a cationic hydrophilic side chain containing from 1to 12 carbon atoms. In some embodiments R₂ can be aliphatic amine,cycloaliphatic amine, heterocyclic amine or aromatic amine, providedthat there is at least one positively charged amine group in the sidechain. R₂ can be the side chain of cationic amino acids such as lysine,arginine and histidine.

Core shell and multi-core shell nanoparticles are provided. Thecore-shell and multi-core shell nanoparticles can contain thepolycations and/or the polycation containing polymers. The core-shelland multi-core shell nanoparticles can contain inorganic particles. Thecore shell and multi-core shell particles can contain additionalpolymers such as hydrophilic polymers, hydrophobic polymers,biodegradable polymers, or a combination thereof. In some embodimentsone or more of the polymers are amphiphilic. In some embodiments thenanoparticles have a diameter between 50 nm and 350 nm or between 10 nmand 1,000 nm.

The nanoparticles can contain one or more cationic particle corescontaining a polycation or a polycation containing polymer. In preferredembodiments the cationic polymer core contains a block copolymer havinga hydrophobic polymer block and a hydrophilic polycation block, e.g. apolylactic-co-glycolic) acid-b-Polycation (PLGA-PC) block copolymer. Thecationic particle core can contain a second polymer containing thehydrophobic polymer without the polycation block. For example, thecationic particle core can contain a PLGA-PC block copolymer and a PLGAhomopolymer.

In some embodiments the core-shell nanoparticles can contain an outerlayer physically attached or chemically conjugated. The outer layer caninclude one or more of a biodegradable polymer, a stealth polymer, alipid, a surfactant, amphiphilic polymer, or a polymer-lipid conjugate.Exemplary embodiments provide a core-shell nanoparticle having (1) acationic particle core; (2) an outer protective layer; and (3) a layeror shell or multiple layers of anionic active agent dispersed betweenthe cationic particle core and the protective layer. In some embodimentsthe core-shell nanoparticle is a multi-core shell nanoparticlecontaining more than one cationic particle core encapsulated by anddispersed within a plurality of anionic active agents.

Formulations a contain an effective amount of the particles foradministration to an individual in need thereof. The formulation can beparenteral formulations. The formulations can be injectableformulations, e.g., solutions or suspensions; solid forms suitable forpreparing solutions or suspensions upon the addition of a reconstitutionmedium prior to injection; emulsions, e.g. water-in-oil (w/o) emulsions,oil-in-water (o/w) emulsions, and microemulsions thereof, liposomes, oremulsomes.

Methods of making the polycations and polycation containing polymers areprovided. In preferred embodiments the method includes thepolycondensation reaction of a bis-(α-amino acid) diester with a di-acidor the activated ester thereof. The di-acid can be succinic acid, adipicacid, or sebacic acid. Methods of making and formulating thenanoparticles are also provided.

The formulations are useful for intracellular delivery, as well asextracellular delivery and systemic delivery to a body or regionaldelivery to an organ or tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts the structure of some exemplary polycations containingarginine, lysine, or histidine side chains.

FIG. 2 depicts the structure of an exemplary PLGA-PC block copolymer(top) and a PLGA-PC-PEG block copolymer (bottom).

FIGS. 3A-3D depict some of the parameters that can be adjusted to alterthe particle properties including, polycation chain length/molecularweight (3A); ratio of PLGA-PC polymer to PLGA polymer (3B); PC:PLGAratio/PLGA molecular weight (3C); and structure of the polycation (3D).

FIGS. 4A-4E depict some of the particle structures that can be producedusing the polycation containing polymers.

FIG. 5 is a schematic depicting formation of small nanoparticles havinga cationic outer later from self-assembly of block copolymers of ahydropobic biodegradable polymer (PLGA) and a polycation (PC). The smallnanoparticles self-assemble with anionic active agents such as proteins,nucleic acids, or peptides to form a multinuclear PLGA-PC/proteinnanosphere.

FIG. 6 is a scheme depicting the synthesis of some L-arginine-basedpolycations (PC) (steps 1-3) and PLGA-b-PC copolymers (step 4).

FIG. 7 is a graph depicting the particle size (nm) distribution of thepoly(lactide-co-glycolide) (PLGA) and PLGA-block-polycation (PLGA-b-PC)nanoparticles measured by dynamic light scattering.

FIG. 8 is a graph depicting the dependence of the particle size (nm;bars) and the zeta potential (mV; line) on the ratio (w/w) of PLGA-PCpolymer to bovine serum albumin (BSA) protein for PLGA-1-PC-16/BSAparticles.

FIG. 9 is a graph depicting the dependence of the particle size (nm;bars) and the zeta potential (mV; line) on the ratio (w/w) of PLGA-PCpolymer to bovine serum albumin (BSA) protein for PLGA-2-PC-16/BSAparticles.

FIG. 10 is a graph depicting the release profile of PLGA-PC NP/BSA/LipidPEG in PBS buffer.

FIG. 11 is a bar graph depicting the dependence of the zeta potential(mV) on the ratio (w/w) of PLGA-b-PEG to PLGA-b-PC. The PEG is 3.4K.

FIG. 12 is a bar graph depicting the dependence of the zeta potential(mV) on the ratio (w/w) of PLGA-b-PEG to PLGA-b-PC. The PEG is 2K.

FIG. 13 is a bar graph depicting the dependence of the particle size(nm) from dynamic light scattering on the ratio (w/w) of PLGA-b-PEG toPLGA-b-PC. The PEG is 3.4K.

FIG. 14 is a bar graph depicting the dependence of the particle size(nm) from dynamic light scattering on the ratio (w/w) of PLGA-b-PEG toPLGA-b-PC. The PEG is 2K.

FIG. 15 is a graph of the cumulative insulin release (%) as a functionof time (days) for PLGA-PC/insulin nanoparticles prepared bynanoprecipitation.

FIG. 16 is a graph of the cumulative insulin release (%) as a functionof time (days) for PLGA-PC/insulin nanoparticles prepared by doubleemulsion.

DETAILED DESCRIPTION OF THE INVENTION

A polymeric nanoparticle platform is provided for delivery of negativelycharged active agents such as proteins and nucleic acids. Thenanoparticles can exhibit one or more of: (1) high loading efficiencythereby reducing required nanoparticle mass to achieve therapeutic dose;(2) no or limited organic solvents used during formulation to preventdenaturation; (3) minimal contact with carriers to avoid unwantedinteractions or relatively low local pH environment caused by polymerdegradation; and (4) sustainable and controllable release with lowinitial burst.

I. Definitions

The terms “subject” or “patient”, as used herein, refer to any organismto which the particles may be administered, e.g. for experimental,therapeutic, diagnostic, and/or prophylactic purposes. Typical subjectsinclude animals (e.g., mammals such as mice, rats, rabbits, non-humanprimates, and humans) and/or plants.

The terms “treating” or “preventing”, as used herein, can includepreventing a disease, disorder or condition from occurring in an animalwhich may be predisposed to the disease, disorder and/or condition buthas not yet been diagnosed as having it; inhibiting the disease,disorder or condition, e.g., impeding its progress; and relieving thedisease, disorder, or condition, e.g., causing regression of thedisease, disorder and/or condition. Treating the disease, disorder, orcondition can include ameliorating at least one symptom of theparticular disease, disorder, or condition, even if the underlyingpathophysiology is not affected, such as treating the pain of a subjectby administration of an analgesic agent even though such agent does nottreat the cause of the pain.

The term “altered level of expression” of a marker, protein or generefers to an expression level in a test sample (e.g., a sample derivedfrom a subject during or following treatment for a metabolic disorder,such as diabetes and/or obesity), that is greater or less than thestandard error of the assay employed to assess expression and may be atleast two, five, s ten times, 100, 500 or 1000 times the expressionlevel in a control sample (e.g., a sample from the subject prior totreatment), or the average expression level of the marker in severalcontrol samples.

An “exogenous” molecule is a molecule that is not normally present in acell, but can be introduced into a cell by one or more genetic,biochemical or other methods. “Normal presence in the cell” isdetermined with respect to the particular developmental stage andenvironmental conditions of the cell. Thus, for example, a molecule thatis present only during embryonic development of muscle is an exogenousmolecule with respect to an adult muscle cell. Similarly, a moleculeinduced by heat shock is an exogenous molecule with respect to anon-heat-shocked cell. An exogenous molecule can comprise, for example,a functioning version of a malfunctioning endogenous molecule, amalfunctioning version of a normally-functioning endogenous molecule oran ortholog (functioning version of endogenous molecule from a differentspecies).

“Parenteral administration”, as used herein, means administration by anymethod other than through the digestive tract or non-invasive topical orregional routes. For example, parenteral administration may includeadministration to a patient intravenously, intradermally,intraperitoneally, intrapleurally, intratracheally, intramuscularly,subcutaneously, subjunctivally, by injection, and by infusion.

“Topical administration”, as used herein, means the non-invasiveadministration to the skin, orifices, or mucosa. Topical administrationscan be administered locally, i.e. they are capable of providing a localeffect in the region of application without systemic exposure. Topicalformulations can provide systemic effect via adsorption into the bloodstream of the individual. Topical administration can include, but is notlimited to, cutaneous and transdermal administration, buccaladministration, intranasal administration, intravaginal administration,intravesical administration, ophthalmic administration, and rectaladministration.

transdermal

“Enteral administration”, as used herein, means administration viaabsorption through the gastrointestinal tract. Enteral administrationcan include oral and sublingual administration, gastric administration,or rectal administration.

“Pulmonary administration”, as used herein, means administration intothe lungs by inhalation or endotracheal administration. As used herein,the term “inhalation” refers to intake of air to the alveoli. The intakeof air can occur through the mouth or nose.

The terms “sufficient” and “effective”, as used interchangeably herein,refer to an amount (e.g. mass, volume, dosage, concentration, and/ortime period) needed to achieve one or more desired result(s). A“therapeutically effective amount” is at least the minimum concentrationrequired to effect a measurable improvement or prevention of any symptomor a particular condition or disorder, to effect a measurableenhancement of life expectancy, or to generally improve patient qualityof life. The therapeutically effective amount is thus dependent upon thespecific biologically active molecule and the specific condition ordisorder to be treated. Therapeutically effective amounts of many activeagents, such as antibodies, are well known in the art. Thetherapeutically effective amounts of anionic proteins, proteinanalogues, or nucleic acids hereinafter discovered or for treatingspecific disorders with known proteins, protein analogues, or nucleicacids to treat additional disorders may be determined by standardtechniques which are well within the craft of a skilled artisan, such asa physician.

The terms “bioactive agent” and “active agent”, as used interchangeablyherein, include, without limitation, physiologically orpharmacologically active substances that act locally or systemically inthe body. A bioactive agent is a substance used for the treatment (e.g.,therapeutic agent), prevention (e.g., prophylactic agent), diagnosis(e.g., diagnostic agent), cure or mitigation of disease or illness, asubstance which affects the structure or function of the body, orpro-drugs, which become biologically active or more active after theyhave been placed in a predetermined physiological environment.

The term “prodrug” refers to an agent, including nucleic acids andproteins, which is converted into a biologically active form in vitroand/or in vivo. Prodrugs are often useful because, in some situations,they may be easier to administer than the parent compound. They may, forinstance, be bioavailable by oral administration whereas the parentcompound is not. The prodrug may also have improved solubility inpharmaceutical compositions over the parent drug. A prodrug may beconverted into the parent drug by various mechanisms, includingenzymatic processes and metabolic hydrolysis. Harper, N. J. (1962). DrugLatentiation in Jucker, ed. Progress in Drug Research, 4:221-294;Morozowich et al. (1977). Application of Physical Organic Principles toProdrug Design in E. B. Roche ed. Design of Biopharmaceutical Propertiesthrough Prodrugs and Analogs, APhA; Acad. Pharm. Sci.; E. B. Roche, ed.(1977). Bioreversible Carriers in Drug in Drug Design, Theory andApplication, APhA; H. Bundgaard, ed. (1985) Design of Prodrugs,Elsevier; Wang et al. (1999) Prodrug approaches to the improved deliveryof peptide drug, Curr. Pharm. Design. 5(4):265-287; Pauletti et al.(1997). Improvement in peptide bioavailability: Peptidomimetics andProdrug Strategies, Adv. Drug. Delivery Rev. 27:235-256; Mizen et al.(1998). The Use of Esters as Prodrugs for Oral Delivery of β-Lactamantibiotics, Pharm. Biotech. 11:345-365; Gaignault et al. (1996).Designing Prodrugs and Bioprecursors I. Carrier Prodrugs, Pract. Med.Chem. 671-696; M. Asgharnejad (2000). Improving Oral Drug Transport ViaProdrugs, in G. L. Amidon, P. I. Lee and E. M. Topp, Eds., TransportProcesses in Pharmaceutical Systems, Marcell Dekker, p. 185-218; Balantet al. (1990) Prodrugs for the improvement of drug absorption viadifferent routes of administration, Eur. J. Drug Metab. Pharmacokinet.,15(2): 143-53; Balimane and Sinko (1999). Involvement of multipletransporters in the oral absorption of nucleoside analogues, Adv. DrugDelivery Rev., 39(1-3):183-209; Browne (1997). Fosphenytoin (Cerebyx),Clin. Neuropharmacol. 20(1): 1-12; Bundgaard (1979). Bioreversiblederivatization of drugs—principle and applicability to improve thetherapeutic effects of drugs, Arch. Pharm. Chemi. 86(1): 1-39; H.Bundgaard, ed. (1985) Design of Prodrugs, New York: Elsevier; Fleisheret al. (1996). Improved oral drug delivery: solubility limitationsovercome by the use of prodrugs, Adv. Drug Delivery Rev. 19(2): 115-130;Fleisher et al. (1985). Design of prodrugs for improved gastrointestinalabsorption by intestinal enzyme targeting, Methods Enzymol. 112: 360-81;Farquhar D, et al. (1983). Biologically Reversible Phosphate-ProtectiveGroups, J. Pharm. Sci., 72(3): 324-325; Han, H. K. et al. (2000).Targeted prodrug design to optimize drug delivery, AAPS PharmSci., 2(1):E6; Sadzuka Y. (2000). Effective prodrug liposome and conversion toactive metabolite, Curr. Drug Metab., 1(1):31-48; D. M. Lambert (2000)Rationale and applications of lipids as prodrug carriers, Eur. J. Pharm.Sci., 11 Suppl. 2:S15-27; Wang, W. et al. (1999) Prodrug approaches tothe improved delivery of peptide drugs. Curr. Pharm. Des., 5(4):265-87.

The term “biocompatible”, as used herein, refers to a material thatalong with any metabolites or degradation products thereof that aregenerally non-toxic to the recipient and do not cause any significantadverse effects to the recipient. Generally speaking, biocompatiblematerials are materials which do not elicit a significant inflammatoryor immune response when administered to a patient.

The term “biodegradable” as used herein, generally refers to a materialthat will degrade or erode under physiologic conditions to smaller unitsor chemical species that are capable of being metabolized, eliminated,or excreted by the subject. The degradation time is a function ofcomposition and morphology. Degradation times can be from hours toweeks.

The term “pharmaceutically acceptable”, as used herein, refers tocompounds, materials, compositions, and/or dosage forms which are,within the scope of sound medical judgment, suitable for use in contactwith the tissues of human beings and animals without excessive toxicity,irritation, allergic response, or other problems or complicationscommensurate with a reasonable benefit/risk ratio, in accordance withthe guidelines of agencies such as the Food and Drug Administration. A“pharmaceutically acceptable carrier”, as used herein, refers to allcomponents of a pharmaceutical formulation which facilitate the deliveryof the composition in vivo. Pharmaceutically acceptable carriersinclude, but are not limited to, diluents, preservatives, binders,lubricants, disintegrators, swelling agents, fillers, stabilizers, andcombinations thereof.

The term “molecular weight”, as used herein, generally refers to themass or average mass of a material. If a polymer or oligomer, themolecular weight can refer to the relative average chain length orrelative chain mass of the bulk polymer. In practice, the molecularweight of polymers and oligomers can be estimated or characterized invarious ways including gel permeation chromatography (GPC) or capillaryviscometry. GPC molecular weights are reported as the weight-averagemolecular weight (M_(w)) as opposed to the number-average molecularweight (M_(n)). Capillary viscometry provides estimates of molecularweight as the inherent viscosity determined from a dilute polymersolution using a particular set of concentration, temperature, andsolvent conditions.

The term “small molecule”, as used herein, generally refers to anorganic molecule that is less than about 2000 g/mol in molecular weight,less than about 1500 g/mol, less than about 1000 g/mol, less than about800 g/mol, or less than about 500 g/mol. Small molecules arenon-polymeric and/or non-oligomeric.

The term “hydrophilic”, as used herein, refers to substances that havestrongly polar groups that readily interact with water.

The term “hydrophobic”, as used herein, refers to substances that lackan affinity for water; tending to repel and not absorb water as well asnot dissolve in or mix with water.

The term “lipophilic”, as used herein, refers to compounds having anaffinity for lipids.

The term “amphiphilic”, as used herein, refers to a molecule combininghydrophilic and lipophilic (hydrophobic) properties. “Amphiphilicmaterial” as used herein refers to a material containing a hydrophobicor more hydrophobic oligomer or polymer (e.g., biodegradable oligomer orpolymer) and a hydrophilic or more hydrophilic oligomer or polymer.

The term “targeting moiety”, as used herein, refers to a moiety thatbinds to or localizes to a specific locale. The moiety may be, forexample, a protein, nucleic acid, nucleic acid analog, carbohydrate, orsmall molecule. The locale may be a tissue, a particular cell type, or asubcellular compartment. The targeting moiety or a sufficient pluralityof targeting moieties may be used to direct the localization of aparticle or an active entity. The active entity may be useful fortherapeutic, prophylactic, or diagnostic purposes.

The term “reactive coupling group”, as used herein, refers to anychemical functional group capable of reacting with a second functionalgroup to form a covalent bond. The selection of reactive coupling groupsis within the ability of the skilled artisan. Examples of reactivecoupling groups can include primary amines (—NH₂) and amine-reactivelinking groups such as isothiocyanates, isocyanates, acyl azides, NHSesters, sulfonyl chlorides, aldehydes, glyoxals, epoxides, oxiranes,carbonates, aryl halides, imidoesters, carbodiimides, anhydrides, andfluorophenyl esters. Most of these conjugate to amines by eitheracylation or alkylation. Examples of reactive coupling groups caninclude aldehydes (—COH) and aldehyde reactive linking groups such ashydrazides, alkoxyamines, and primary amines. Examples of reactivecoupling groups can include thiol groups (—SH) and sulfhydryl reactivegroups such as maleimides, haloacetyls, and pyridyl disulfides. Examplesof reactive coupling groups can include photoreactive coupling groupssuch as aryl azides or diazirines. The coupling reaction may include theuse of a catalyst, heat, pH buffers, light, or a combination thereof.

The term “protective group”, as used herein, refers to a functionalgroup that can be added to and/or substituted for another desiredfunctional group to protect the desired functional group from certainreaction conditions and selectively removed and/or replaced to deprotector expose the desired functional group. Protective groups are known tothe skilled artisan. Suitable protective groups may include thosedescribed in Greene, T. W. and Wuts, P.G.M., Protective Groups inOrganic Synthesis, (1991). Acid sensitive protective groups includedimethoxytrityl (DMT), tert-butylcarbamate (tBoc) and trifluoroacetyl(tFA). Base sensitive protective groups include9-fluorenylmethoxycarbonyl (Fmoc), isobutyrl (iBu), benzoyl (Bz) andphenoxyacetyl (pac). Other protective groups include acetamidomethyl,acetyl, tert-amyloxycarbonyl, benzyl, benzyloxycarbonyl,2-(4-biphenylyl)-2-propyloxycarbonyl, 2-bromobenzyloxycarbonyl,tert-butyl₇ tert-butyloxycarbonyl,1-carbobenzoxamido-2,2.2-trifluoroethyl, 2,6-dichlorobenzyl,2-(3,5-dimethoxyphenyl)-2-propyloxycarbonyl, 2,4-dinitrophenyl,dithiasuccinyl, formyl, 4-methoxybenzenesulfonyl, 4-methoxybenzyl,4-methylbenzyl, o-nitrophenylsulfenyl, 2-phenyl-2-propyloxycarbonyl,α-2,4,5-tetramethylbenzyloxycarbonyl, p-toluenesulfonyl, xanthenyl,benzyl ester, N-hydroxysuccinimide ester, p-nitrobenzyl ester,p-nitrophenyl ester, phenyl ester, p-nitrocarbonate,p-nitrobenzylcarbonate, trimethylsilyl and pentachlorophenyl ester.

The term “activated ester”, as used herein, refers to alkyl esters ofcarboxylic acids where the alkyl is a good leaving group rendering thecarbonyl susceptible to nucleophilic attack by molecules bearing aminogroups. Activated esters are therefore susceptible to aminolysis andreact with amines to form amides. Activated esters contain a carboxylicacid ester group —CO₂R where R is the leaving group.

The term “alkyl” refers to the radical of saturated aliphatic groups,including straight-chain alkyl groups, branched-chain alkyl groups,cycloalkyl (alicyclic) groups, alkyl-substituted cycloalkyl groups, andcycloalkyl-substituted alkyl groups.

In preferred embodiments, a straight chain or branched chain alkyl has100 or fewer such as 30 or fewer carbon atoms in its backbone (e.g.,C₁-C₁₀₀ for straight chains, C₃-C₁₀₀ for branched chains), preferably 50or fewer, more preferably 25 or fewer, most preferably 12 or fewer.Likewise, preferred cycloalkyls have from 3-10 carbon atoms in theirring structure, and more preferably have 5, 6 or 7 carbons in the ringstructure. The term “alkyl” (or “lower alkyl”) as used throughout thespecification, examples, and claims is intended to include both“unsubstituted alkyls” and “substituted alkyls”, the latter of whichrefers to alkyl moieties having one or more substituents replacing ahydrogen on one or more carbons of the hydrocarbon backbone. Suchsubstituents include, but are not limited to, halogen, hydroxyl,carbonyl (such as a carboxyl, alkoxycarbonyl, formyl, or an acyl),thiocarbonyl (such as a thioester, a thioacetate, or a thioformate),alkoxyl, phosphoryl, phosphate, phosphonate, a hosphinate, amino, amido,amidine, imine, cyano, nitro, azido, sulfhydryl, alkylthio, sulfate,sulfonate, sulfamoyl, sulfonamido, sulfonyl, heterocyclyl, aralkyl, oran aromatic or heteroaromatic moiety.

Unless the number of carbons is otherwise specified, “lower alkyl” asused herein means an alkyl group, as defined above, but having from oneto ten carbons, more preferably from one to six carbon atoms in itsbackbone structure. Likewise, “lower alkenyl” and “lower alkynyl” havesimilar chain lengths. Throughout the application, preferred alkylgroups are lower alkyls. In preferred embodiments, a substituentdesignated herein as alkyl is a lower alkyl.

It will be understood by those skilled in the art that the moietiessubstituted on the hydrocarbon chain can themselves be substituted, ifappropriate. For instance, the substituents of a substituted alkyl mayinclude halogen, hydroxy, nitro, thiols, amino, azido, imino, amido,phosphoryl (including phosphonate and phosphinate), sulfonyl (includingsulfate, sulfonamido, sulfamoyl and sulfonate), and silyl groups, aswell as ethers, alkylthios, carbonyls (including ketones, aldehydes,carboxylates, and esters),

—CF₃, —CN and the like. Cycloalkyls can be substituted in the samemanner.

The term “heteroalkyl”, as used herein, refers to straight or branchedchain, or cyclic carbon-containing radicals, or combinations thereof,containing at least one heteroatom. Suitable heteroatoms include, butare not limited to, O, N, Si, P, Se, B, and S, wherein the phosphorousand sulfur atoms are optionally oxidized, and the nitrogen heteroatom isoptionally quaternized. Heteroalkyls can be substituted as defined abovefor alkyl groups.

The term “alkylthio” refers to an alkyl group, as defined above, havinga sulfur radical attached thereto. In preferred embodiments, the“alkylthio” moiety is represented by one of —S-alkyl, —S-alkenyl, and—S-alkynyl. Representative alkylthio groups include methylthio,ethylthio, and the like. The term “alkylthio” also encompassescycloalkyl groups, alkene and cycloalkene groups, and alkyne groups.“Arylthio” refers to aryl or heteroaryl groups. Alkylthio groups can besubstituted as defined above for alkyl groups.

The terms “alkenyl” and “alkynyl”, refer to unsaturated aliphatic groupsanalogous in length and possible substitution to the alkyls describedabove, but that contain at least one double or triple bond respectively.

The terms “alkoxyl” or “alkoxy” as used herein refers to an alkyl group,as defined above, having an oxygen radical attached thereto.Representative alkoxyl groups include methoxy, ethoxy, propyloxy,tert-butoxy and the like. An “ether” is two hydrocarbons covalentlylinked by an oxygen. Accordingly, the substituent of an alkyl thatrenders that alkyl an ether is or resembles an alkoxyl, such as can berepresented by one of —O— alkyl, —O-alkenyl, and —O-alkynyl. Aroxy canbe represented by —O-aryl or O-heteroaryl, wherein aryl and heteroarylare as defined below. The alkoxy and aroxy groups can be substituted asdescribed above for alkyl.

The terms “amine” and “amino” are art-recognized and refer to bothunsubstituted and substituted amines, e.g., a moiety that can berepresented by the general formula:

wherein R₉, R₁₀, and R′₁₀ each independently represent a hydrogen, analkyl, an alkenyl, —(CH₂)_(m)—R₈ or R₉ and R₁₀ taken together with the Natom to which they are attached complete a heterocycle having from 4 to8 atoms in the ring structure; R₈ represents an aryl, a cycloalkyl, acycloalkenyl, a heterocycle or a polycycle; and m is zero or an integerin the range of 1 to 8. In preferred embodiments, only one of R₉ or R₁₀can be a carbonyl, e.g., R₉, R₁₀ and the nitrogen together do not forman imide. In still more preferred embodiments, the term “amine” does notencompass amides, e.g., wherein one of R₉ and R₁₀ represents a carbonyl.In even more preferred embodiments, R₉ and R₁₀ (and optionally R′₁₀)each independently represent a hydrogen, an alkyl or cycloakly, analkenyl or cycloalkenyl, or alkynyl. Thus, the term “alkylamine” as usedherein means an amine group, as defined above, having a substituted (asdescribed above for alkyl) or unsubstituted alkyl attached thereto,i.e., at least one of R₉ and R₁₀ is an alkyl group.

The term “amido” is art-recognized as an amino-substituted carbonyl andincludes a moiety that can be represented by the general formula:

wherein R₉ and R₁₀ are as defined above.

“Aryl”, as used herein, refers to C₅-C₁₀-membered aromatic,heterocyclic, fused aromatic, fused heterocyclic, biaromatic, orbihetereocyclic ring systems. Broadly defined, “aryl”, as used herein,includes 5-, 6-, 7-, 8-, 9-, and 10-membered single-ring aromatic groupsthat may include from zero to four heteroatoms, for example, benzene,pyrrole, furan, thiophene, imidazole, oxazole, thiazole, triazole,pyrazole, pyridine, pyrazine, pyridazine and pyrimidine, and the like.Those aryl groups having heteroatoms in the ring structure may also bereferred to as “aryl heterocycles” or “heteroaromatics”. The aromaticring can be substituted at one or more ring positions with one or moresubstituents including, but not limited to, halogen, azide, alkyl,aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl, amino (orquaternized amino), nitro, sulfhydryl, imino, amido, phosphonate,phosphinate, carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl,sulfonamido, ketone, aldehyde, ester, heterocyclyl, aromatic orheteroaromatic moieties, —CF₃, —CN; and combinations thereof.

The term “aryl” also includes polycyclic ring systems having two or morecyclic rings in which two or more carbons are common to two adjoiningrings (i.e., “fused rings”) wherein at least one of the rings isaromatic, e.g., the other cyclic ring or rings can be cycloalkyls,cycloalkenyls, cycloalkynyls, aryls and/or heterocycles. Examples ofheterocyclic rings include, but are not limited to, benzimidazolyl,benzofuranyl, benzothiofuranyl, benzothiophenyl, benzoxazolyl,benzoxazolinyl, benzthiazolyl, benztriazolyl, benztetrazolyl,benzisoxazolyl, benzisothiazolyl, benzimidazolinyl, carbazolyl, 4aHcarbazolyl, carbolinyl, chromanyl, chromenyl, cinnolinyl,decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl, dihydrofuro[2,3b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl, imidazolinyl,imidazolyl, 1H-indazolyl, indolenyl, indolinyl, indolizinyl, indolyl,3H-indolyl, isatinoyl, isobenzofuranyl, isochromanyl, isoindazolyl,isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl, isoxazolyl,methylenedioxyphenyl, morpholinyl, naphthyridinyl,octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl,1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl,oxazolyl, oxindolyl, pyrimidinyl, phenanthridinyl, phenanthrolinyl,phenazinyl, phenothiazinyl, phenoxathinyl, phenoxazinyl, phthalazinyl,piperazinyl, piperidinyl, piperidonyl, 4-piperidonyl, piperonyl,pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl,pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothiazole,pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, 2H-pyrrolyl,pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxalinyl,quinuclidinyl, tetrahydrofuranyl, tetrahydroisoquinolinyl,tetrahydroquinolinyl, tetrazolyl, 6H-1,2,5-thiadiazinyl,1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl,1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl,thienooxazolyl, thienoimidazolyl, thiophenyl and xanthenyl. One or moreof the rings can be substituted as defined above for “aryl”.

The term “aralkyl”, as used herein, refers to an alkyl group substitutedwith an aryl group (e.g., an aromatic or heteroaromatic group).

The term “carbocycle”, as used herein, refers to an aromatic ornonaromatic ring in which each atom of the ring is carbon.

“Heterocycle” or “heterocyclic”, as used herein, refers to a cyclicradical attached via a ring carbon or nitrogen of a monocyclic orbicyclic ring containing 3-10 ring atoms, and preferably from 5-6 ringatoms, consisting of carbon and one to four heteroatoms each selectedfrom the group consisting of non-peroxide oxygen, sulfur, and N(Y)wherein Y is absent or is H, O, (C₁-C₁₀) alkyl, phenyl or benzyl, andoptionally containing 1-3 double bonds and optionally substituted withone or more substituents. Examples of heterocyclic ring include, but arenot limited to, benzimidazolyl, benzofuranyl, benzothiofuranyl,benzothiophenyl, benzoxazolyl, benzoxazolinyl, benzthiazolyl,benztriazolyl, benztetrazolyl, benzisoxazolyl, benzisothiazolyl,benzimidazolinyl, carbazolyl, 4aH-carbazolyl, carbolinyl, chromanyl,chromenyl, cinnolinyl, decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl,dihydrofuro[2,3-b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl,imidazolinyl, imidazolyl, 1H-indazolyl, indolenyl, indolinyl,indolizinyl, indolyl, 3H-indolyl, isatinoyl, isobenzofuranyl,isochromanyl, isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl,isothiazolyl, isoxazolyl, methylenedioxyphenyl, morpholinyl,naphthyridinyl, octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl,1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl,oxazolyl, oxepanyl, oxetanyl, oxindolyl, pyrimidinyl, phenanthridinyl,phenanthrolinyl, phenazinyl, phenothiazinyl, phenoxathinyl,phenoxazinyl, phthalazinyl, piperazinyl, piperidinyl, piperidonyl,4-piperidonyl, piperonyl, pteridinyl, purinyl, pyranyl, pyrazinyl,pyrazolidinyl, pyrazolinyl, pyrazolyl, pyridazinyl, pyridooxazole,pyridoimidazole, pyridothiazole, pyridinyl, pyridyl, pyrimidinyl,pyrrolidinyl, pyrrolinyl, 2H-pyrrolyl, pyrrolyl, quinazolinyl,quinolinyl, 4H-quinolizinyl, quinoxalinyl, quinuclidinyl,tetrahydrofuranyl, tetrahydroisoquinolinyl, tetrahydropyranyl,tetrahydroquinolinyl, tetrazolyl, 6H-1,2,5-thiadiazinyl,1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl,1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl,thienooxazolyl, thienoimidazolyl, thiophenyl and xanthenyl. Heterocyclicgroups can optionally be substituted with one or more substituents atone or more positions as defined above for alkyl and aryl, for example,halogen, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, amino,nitro, sulfhydryl, imino, amido, phosphate, phosphonate, phosphinate,carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl, ketone, aldehyde,ester, a heterocyclyl, an aromatic or heteroaromatic moiety, —CF3, —CN,or the like.

The term “carbonyl” is art-recognized and includes such moieties as canbe represented by the general formula:

wherein X is a bond or represents an oxygen or a sulfur, and R₁₁represents a hydrogen, an alkyl, a cycloalkyl, an alkenyl, ancycloalkenyl, or an alkynyl, R′₁₁ represents a hydrogen, an alkyl, acycloalkyl, an alkenyl, an cycloalkenyl, or an alkynyl. Where X is anoxygen and R₁₁ or R′₁₁ is not hydrogen, the formula represents an“ester”. Where X is an oxygen and R₁₁ is as defined above, the moiety isreferred to herein as a carboxyl group, and particularly when R₁₁ is ahydrogen, the formula represents a “carboxylic acid”. Where X is anoxygen and R′₁₁ is hydrogen, the formula represents a “formate”. Ingeneral, where the oxygen atom of the above formula is replaced bysulfur, the formula represents a “thiocarbonyl” group. Where X is asulfur and R₁₁ or R′₁₁ is not hydrogen, the formula represents a“thioester.” Where X is a sulfur and R₁₁ is hydrogen, the formularepresents a “thiocarboxylic acid.” Where X is a sulfur and R′₁₁ ishydrogen, the formula represents a “thioformate.” On the other hand,where X is a bond, and R₁₁ is not hydrogen, the above formula representsa “ketone” group. Where X is a bond, and R₁₁ is hydrogen, the aboveformula represents an “aldehyde” group.

The term “heteroatom” as used herein means an atom of any element otherthan carbon or hydrogen. Preferred heteroatoms are boron, nitrogen,oxygen, phosphorus, sulfur and selenium. Other heteroatoms includesilicon and arsenic.

As used herein, the term “nitro” means —NO₂; the term “halogen”designates —F, —Cl, —Br or —I; the term “sulfhydryl” means —SH; the term“hydroxyl” means —OH; and the term “sulfonyl” means —SO₂—.

The term “substituted” as used herein, refers to all permissiblesubstituents of the compounds described herein. In the broadest sense,the permissible substituents include acyclic and cyclic, branched andunbranched, carbocyclic and heterocyclic, aromatic and nonaromaticsubstituents of organic compounds. Illustrative substituents include,but are not limited to, halogens, hydroxyl groups, or any other organicgroupings containing any number of carbon atoms, preferably 1-14 carbonatoms, and optionally include one or more heteroatoms such as oxygen,sulfur, or nitrogen grouping in linear, branched, or cyclic structuralformats. Representative substituents include alkyl, substituted alkyl,alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, phenyl,substituted phenyl, aryl, substituted aryl, heteroaryl, substitutedheteroaryl, halo, hydroxyl, alkoxy, substituted alkoxy, phenoxy,substituted phenoxy, aroxy, substituted aroxy, alkylthio, substitutedalkylthio, phenylthio, substituted phenylthio, arylthio, substitutedarylthio, cyano, isocyano, substituted isocyano, carbonyl, substitutedcarbonyl, carboxyl, substituted carboxyl, amino, substituted amino,amido, substituted amido, sulfonyl, substituted sulfonyl, sulfonic acid,phosphoryl, substituted phosphoryl, phosphonyl, substituted phosphonyl,polyaryl, substituted polyaryl, C₃-C₂₀ cyclic, substituted C₃-C₂₀cyclic, heterocyclic, substituted heterocyclic, aminoacid, peptide, andpolypeptide groups.

Heteroatoms such as nitrogen may have hydrogen substituents and/or anypermissible substituents of organic compounds described herein whichsatisfy the valences of the heteroatoms. It is understood that“substitution” or “substituted” includes the implicit proviso that suchsubstitution is in accordance with permitted valence of the substitutedatom and the substituent, and that the substitution results in a stablecompound, i.e. a compound that does not spontaneously undergotransformation such as by rearrangement, cyclization, elimination, etc.

The term “copolymer” as used herein, generally refers to a singlepolymeric material that is comprised of two or more different monomers.The copolymer can be of any form, such as random, block, graft, etc. Thecopolymers can have any end-group, including capped or acid end groups.

The term “mean particle size”, as used herein, generally refers to thestatistical mean particle size (diameter) of the particles in thecomposition. The diameter of an essentially spherical particle may bereferred to as the physical or hydrodynamic diameter. The diameter of anon-spherical particle may refer preferentially to the hydrodynamicdiameter. As used herein, the diameter of a non-spherical particle mayrefer to the largest linear distance between two points on the surfaceof the particle. Mean particle size can be measured using methods knownin the art, such as dynamic light scattering. Two populations can besaid to have a “substantially equivalent mean particle size” when thestatistical mean particle size of the first population of nanoparticlesis within 20% of the statistical mean particle size of the secondpopulation of nanoparticles; more preferably within 15%, most preferablywithin 10%.

The terms “monodisperse” and “homogeneous size distribution”, as usedinterchangeably herein, describe a population of particles,microparticles, or nanoparticles all having the same or nearly the samesize. As used herein, a monodisperse distribution refers to particledistributions in which 90% of the distribution lies within 5% of themean particle size.

The terms “polypeptide,” “peptide” and “protein” generally refer to apolymer of amino acid residues. As used herein, the term also applies toamino acid polymers in which one or more amino acids are chemicalanalogues or modified derivatives of corresponding naturally-occurringamino acids. The term “protein”, as generally used herein, refers to apolymer of amino acids linked to each other by peptide bonds to form apolypeptide for which the chain length is sufficient to produce tertiaryand/or quaternary structure. The term “protein” excludes small peptidesby definition, the small peptides lacking the requisite higher-orderstructure necessary to be considered a protein.

The terms “nucleic acid,” “polynucleotide,” and “oligonucleotide” areused interchangeably to refer to a deoxyribonucleotide or ribonucleotidepolymer, in linear or circular conformation, and in either single- ordouble-stranded form. These terms are not to be construed as limitingwith respect to the length of a polymer. The terms can encompass knownanalogues of natural nucleotides, as well as nucleotides that aremodified in the base, sugar and/or phosphate moieties (e.g.,phosphorothioate backbones). In general and unless otherwise specified,an analogue of a particular nucleotide has the same base-pairingspecificity; i.e., an analogue of A will base-pair with T. The term“nucleic acid” is a term of art that refers to a string of at least twobase-sugar-phosphate monomeric units. Nucleotides are the monomericunits of nucleic acid polymers. The term includes deoxyribonucleic acid(DNA) and ribonucleic acid (RNA) in the form of a messenger RNA,anti-sense, plasmid DNA, parts of a plasmid DNA or genetic materialderived from a virus. Anti-sense is a polynucleotide that interfereswith the function of DNA and/or RNA. The term nucleic acids-refers to astring of at least two base-sugar-phosphate combinations. Naturalnucleic acids have a phosphate backbone, artificial nucleic acids maycontain other types of backbones, but contain the same bases. The termalso includes PNAs (peptide nucleic acids), phosphorothioates, and othervariants of the phosphate backbone of native nucleic acids.

A “functional fragment” of a protein, polypeptide or nucleic acid is aprotein, polypeptide or nucleic acid whose sequence is not identical tothe full-length protein, polypeptide or nucleic acid, yet retains thesame function as the full-length protein, polypeptide or nucleic acid. Afunctional fragment can possess more, fewer, or the same number ofresidues as the corresponding native molecule, and/or can contain one ormore amino acid or nucleotide substitutions. Methods for determining thefunction of a nucleic acid (e.g., coding function, ability to hybridizeto another nucleic acid) are well-known in the art. Similarly, methodsfor determining protein function are well-known. For example, theDNA-binding function of a polypeptide can be determined, for example, byfilter-binding, electrophoretic mobility-shift, or immunoprecipitationassays. DNA cleavage can be assayed by gel electrophoresis. The abilityof a protein to interact with another protein can be determined, forexample, by co-immunoprecipitation, two-hybrid assays orcomplementation, both genetic and biochemical. See, for example, Fieldset al. (1989) Nature 340:245-246; U.S. Pat. No. 5,585,245 and PCT WO98/44350.

II. Polymers

Cationic polymers are provided for delivering anionic active agents,e.g. in the form or nanoparticles and other nanostructures, or otherpharmaceutical formulations. The polymers can be homopolymers orcopolymers containing a cationic polymer block. The polymers can bebiocompatible and/or biodegradable in whole or in part. The polymer mayhave any molecular weight adjusted dependent upon the specificapplication. The polymer can have a molecular weight between 100 Da and10,000 kDa, between 100 Da and 1,000 kDa, between 1.0 kDa, and 500 kDa,or between 3.0 kDa and 100 kDa.

In some embodiments the polymer is a low molecular weight polymer, e.g.less than 20.0 kDa, less than 15 kDa, less than 12 kDa, or less than 10kDa. The polymers can have a molecular weight between 1.0 kDa and 20.0kDa, e.g. between 1.0 kDa and 12.0 kDa, between 1.0 kDa and 6.0 kDa,between 2.0 kDa and 5.0 kDa, between 3.0 kDa and 4.5 kDa, between 3.5kDa and 4.0 kDa, between 7.0 kDa and 11.0 kDa, between 8.0 kDa and 11.0kDa, between 8.5 kDa and 9.0 kDa, or between 9.0 kDa and 10.0 kDa.

In alternative embodiments the polymer is a high molecular weightpolymer, e.g. greater than 20 kDa, greater than 30 kDa, or greater than40 kDa.

The polymer can have a molecular weight between 40 kDa and 60 kDa,between 45 kDa and 60 kDa, between 45 kDa and 50 kDa, between 48 kDa and49 kDa, between 50 kDa and 60 kDa, or between 50 kDa and 55 kDa.

A. Polycation Polymers

The polymers can be polycations or can be copolymers that include one ormore polycation blocks. The polycation can contain one or more cationicamino acids or amino acid derivatives. The polycation is preferablypositively charged at a physiological pH. The polycation can bepositively charged at neutral and acidic environments. In someembodiments the polycation is positively charged even in most basic pHenvironments. The polycation will generally be positively charged at apH superior to the pKa. The polycation can have a pKa greater than 5.0,greater than 7.0, greater than 9.0, greater than 11.0, greater than11.5, greater than 12.0, or greater than 12.5. In some embodiments thepolycation has a pKa between 5.0 and 12.5, between 5.0 and 10.5, between5.0 and 9.0, or between 6.0 and 8.0.

The polycation or polycation block may have any molecular weight fromabout 100 Da to about 10,000 kDa. The polycation polymer or polycationblock can have a molecular weight less than 1,000 kDa, less than 100kDa, less than 30 kDa, less than 20 kDa, less than 15 kDa, less than 12kDa, or less than 6 kDa.

The polycation can contain dicarboxylic acid ester units and units ofamino acids diesters. The amino acids can be α, β, γ, δ, or ε aminoacids. In preferred embodiments the polycation contains dicarboxylicacid ester units and (α-amino acid)-α,ω-alkylene diester units. Thepolycation can contain 1, 2, 3, or more different types of dicarboxylicacid ester units or amino acid diester units. In some embodiments thepolycation contains only a single type of dicarboxylic acid ester unit,only a single type of amino acid diester units, or both. The molar ratioof dicarobylic acid ester units to (α-amino acid)-α,ω-alkylene diesterunits can be 1 to 1, can be less than 1, or can be greater than 1. Inpreferred embodiments the molar ratio of dicarboxylic acid ester unitsto (α-amino acid)-α,ω-alkylene diester units is between 2:5 and 1:1, isbetween 1:2 and 1:1, or is between 3:5 and 9:10. The ratios can beadjusted to achieve polycations with different end groups.

The (α-amino acid)-α,ω-alkylene diester units include amino acids thatare preferably positively charged at a physiological pH. The (α-aminoacid)-α,ω-alkylene diester units can include amino acids that arepositively charged at neutral and acidic pH, and in some cases arepositively charged at some basic pH. The (α-amino acid)-α,ω-alkylenediester units can include cationic amino acids such as lysine, arginineand histidine as well as analogues thereof such as homolysine,ornithine, diaminobutyric acid, diaminopimelic acid, diaminopropionicacid and homoarginine as well as trimethylysine and trimethylornithine,4-aminopiperidine-4-carboxylic acid,4-amino-1-carbamimidoylpiperidine-4-carboxylic acid and4-guanidinophenylalanine. In some embodiments the (α-aminoacid)-α,ω-alkylene diester units do not include arginine. In someembodiments the (α-amino acid)-α,ω-alkylene diester units do not includelysine. The (α-amino acid)-α,ω-alkylene diester units can includecationic amino acid groups having a pKa greater than 5.0, greater than7.0, greater than 9.0, greater than 11.0, greater than 11.5, greaterthan 12.0, or greater than 12.5. In some embodiments the α-aminoacid)-α,ω-alkylene diester units can include cationic amino acid groupshaving a pKa between 5.0 and 12.5, between 5.0 and 10.5, between 5.0 and9.0, or between 6.0 and 8.0.

The dicarobylic acid ester units can have the structure

where R₁ is a substituted or unsubstituted alkyl, alkenyl, alkynyl,cycloalkyl, heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, aryl, orheteroaryl. In some embodiments R₁ is a substituted or unsubstitutedalkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl,heterocycloalkenyl, aryl, or heteroaryl containing from 1 to 100 carbonatoms, from 1 to 30 carbon atoms, from 1 to 20 carbon atoms, from 1 to12 carbon atoms, or from 2 to 10 carbon atoms. R₁ can be a linear orbranched alkyl, substituted alkyl, alkenyl, substituted alkenyl,alkylene oxide, or substituted alkylene oxide. Exemplary R₁ groupsinclude linear and branched alkyl and substituted alkyl, alkenyl, oralkylene oxide containing from 2 to 20, preferably from 2 to 12 carbonatoms.

The polycation can include (α-amino acid)-α,ω-alkylene diester havingthe structure

where R₁ is a substituted or unsubstituted alkyl, alkenyl, alkynyl,cycloalkyl, heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, aryl, orheteroaryl; and R₂ is a linear or branched alkyl, alkenyl, cycloalkyl,heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, aryl, or heteroarylgroup at least one of which is substituted with one or more cationicprimary, secondary, or tertiary amino groups or quaternary ammonium,sulfonium or phosphinium groups. In some embodiments R₁ is a substitutedor unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocycloalkyl,cycloalkenyl, heterocycloalkenyl, aryl, or heteroaryl containing from 1to 30 carbon atoms, from 1 to 20 carbon atoms, from 1 to 12 carbonatoms, or from 2 to 10 carbon atoms. R₁ can be a linear or branchedalkyl, substituted alkyl, alkenyl, substituted alkenyl, alkylene oxide,or substituted alkylene oxide. Exemplary R₁ groups include linear andbranched alkyl and substituted alkyl, alkenyl, or alkylene oxidecontaining from 2 to 20, preferably from 2 to 12 carbon atoms. Inpreferred embodiments at least one R₂ is a cationic hydrophilic sidechain containing from 1 to 12 carbon atoms. Each R₂ can independently bealiphatic amine, cycloaliphatic amine, heterocyclic amine or aromaticamine, provided that there is at least one positively charged aminegroup in the side chain. The positively charged amine group can have apKa greater than 5.0, greater than 7.0, greater than 9.0, greater than11.0, greater than 11.5, greater than 12.0, or greater than 12.5. Insome embodiments the positively charged amine groups has a pKa between5.0 and 12.5, between 5.0 and 10.5, between 5.0 and 9.0, or between 6.0and 8.0. R₂ can be the side chain of cationic amino acids such aslysine, arginine and histidine, homolysine, ornithine, diaminobutyricacid, diaminopimelic acid, diaminopropionic acid and homoarginine aswell as trimethylysine and trimethylornithine,4-aminopiperidine-4-carboxylic acid,4-amino-1-carbamimidoylpiperidine-4-carboxylic acid and4-guanidinophenylalanine. In some embodiments R₂ is not the side chainof arginine. In some embodiments R₂ is not the side chain of lysine. Insome embodiments, when R₂ is a linear alkyl amine the linear alkyl groupcontains more than 4 carbon atoms.

The polycation or polycation block can include units having thestructure

where each R₁ is independently a substituted or unsubstituted alkyl,alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl,heterocycloalkenyl, aryl, or heteroaryl; each R₂ is independently alinear or branched alkyl, alkenyl, cycloalkyl, heterocycloalkyl,cycloalkenyl, heterocycloalkenyl, aryl, or heteroaryl group substitutedwith one or more cationic primary, secondary, or tertiary amino groupsor quaternary ammonium, sulfonium or phosphinium groups; and n is any aninteger less than about 10,000, preferably less than about 1,000,between 10 and 1,000, more preferably between 10 and 500. In someembodiments R₁ is a substituted or unsubstituted alkyl, alkenyl,alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, heterocycloalkenyl,aryl, or heteroaryl containing from 1 to 30 carbon atoms, from 1 to 20carbon atoms, from 1 to 12 carbon atoms, or from 2 to 10 carbon atoms.R₁ can be a linear or branched alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkylene oxide, or substituted alkylene oxide.Exemplary R₁ groups include linear and branched alkyl and substitutedalkyl, alkenyl, or alkylene oxide containing from 2 to 20, preferablyfrom 2 to 12 carbon atoms. In preferred embodiments R₂ is a cationichydrophilic side chain containing from 1 to 12 carbon atoms. R₂ can bealiphatic amine, cycloaliphatic amine, heterocyclic amine or aromaticamine, provided that there is at least one positively charged aminegroup in the side chain. The positively charged amine group can have apKa greater than 5.0, greater than 7.0, greater than 9.0, greater than11.0, greater than 11.5, greater than 12.0, or greater than 12.5. Insome embodiments the positively charged amine groups has a pKa between5.0 and 12.5, between 5.0 and 10.5, between 5.0 and 9.0, or between 6.0and 8.0. R₂ can be the side chain of cationic amino acids such aslysine, arginine and histidine, homolysine, ornithine, diaminobutyricacid, diaminopimelic acid, diaminopropionic acid and homoarginine aswell as trimethylysine and trimethylornithine,4-aminopiperidine-4-carboxylic acid,4-amino-1-carbamimidoylpiperidine-4-carboxylic acid and4-guanidinophenylalanine. In some embodiments R₂ is not the side chainof arginine. In some embodiments R₂ is not the side chain of lysine. Insome embodiments, when R₂ is a linear alkyl amine the linear alkyl groupcontains more than 4 carbon atoms.

B. Block Copolymers

The polymer can be a block copolymer such as a multi-block, e.g.di-block or a tri-block copolymer including a polycation block asdescribed above with additional polymer blocks that can includehydrophilic polymers, hydrophobic polymers, biodegradable polymers, or acombination thereof. The block copolymer can be amphiphilic, can containan amphiphilic polymer block, or both.

The block copolymer can contain one or more hydrophilic polymers.Hydrophilic polymers include cellulosic polymers such as starch andpolysaccharides; hydrophilic polypeptides; poly(amino acids) such aspoly-L-glutamic acid (PGS), gamma-polyglutamic acid, poly-L-asparticacid, poly-L-serine, or poly-L-lysine; polyalkylene glycols andpolyalkylene oxides such as polyethylene glycol (PEG), polypropyleneglycol (PPG), and poly(ethylene oxide) (PEO); or PLURONIC®, nonionictriblock copolymers composed of a central hydrophobic chain ofpolyoxypropylene (poly(propylene oxide)) flanked by two hydrophilicchains of polyoxyethylene (poly(ethylene oxide)), sold by BASF;poly(oxyethylated polyol); poly(olefinic alcohol);polyvinylpyrrolidone); poly(hydroxyalkylmethacrylamide);poly(hydroxyalkylmethacrylate); poly(saccharides); poly(hydroxy acids);poly(vinyl alcohol), and copolymers thereof.

The block copolymer can contain one or more hydrophobic polymers.Examples of suitable hydrophobic polymers include polyhydroxyacids suchas poly(lactic acid), poly(glycolic acid), and poly(lacticacid-co-glycolic acids); polyhydroxyalkanoates such aspoly3-hydroxybutyrate or poly4-hydroxybutyrate; polycaprolactones;poly(orthoesters); polyanhydrides; poly(phosphazenes);poly(lactide-co-caprolactones); polycarbonates such as tyrosinepolycarbonates; polyamides (including synthetic and natural polyamides),polypeptides, and poly(amino acids); polyesteramides; polyesters;poly(dioxanones); poly(alkylene alkylates); hydrophobic polyethers;polyurethanes; polyetheresters; polyacetals; polycyanoacrylates;polyacrylates; polymethylmethacrylates; polysiloxanes;poly(oxyethylene)/poly(oxypropylene) copolymers; polyketals;polyphosphates; polyhydroxyvalerates; polyalkylene oxalates;polyalkylene succinates; poly(maleic acids), as well as copolymersthereof.

In certain embodiments, the block copolymer contains an aliphaticpolyester. In preferred embodiments, the block copolymer containspoly(lactic acid), poly(glycolic acid), or poly(lactic acid-co-glycolicacid) blocks.

The block copolymer can contain one or more biodegradable polymers.

Biodegradable polymers can include polymers that are insoluble orsparingly soluble in water that are converted chemically orenzymatically in the body into water-soluble materials. Biodegradablepolymers can include soluble polymers crosslinked by hydolyzablecross-linking groups to render the crosslinked polymer insoluble orsparingly soluble in water.

Biodegradable polymers in the block copolymer can include polyamides,polycarbonates, polyalkylenes, polyalkylene glycols, polyalkyleneoxides, polyalkylene terepthalates, polyvinyl alcohols, polyvinylethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone,polyglycolides, polysiloxanes, polyurethanes and copolymers thereof,alkyl cellulose, hydroxyalkyl celluloses, cellulose ethers, celluloseesters, nitro celluloses, polymers of acrylic and methacrylic esters,methyl cellulose, ethyl cellulose, hydroxypropyl cellulose,hydroxy-propyl methyl cellulose, hydroxybutyl methyl cellulose,cellulose acetate, cellulose propionate, cellulose acetate butyrate,cellulose acetate phthalate, carboxylethyl cellulose, cellulosetriacetate, cellulose sulphate sodium salt, poly (methyl methacrylate),poly(ethylmethacrylate), poly(butylmethacrylate),poly(isobutylmethacrylate), poly(hexlmethacrylate),poly(isodecylmethacrylate), poly(lauryl methacrylate), poly (phenylmethacrylate), poly(methyl acrylate), poly(isopropyl acrylate),poly(isobutyl acrylate), poly(octadecyl acrylate), polyethylene,polypropylene poly(ethylene glycol), poly(ethylene oxide), poly(ethyleneterephthalate), poly(vinyl alcohols), poly(vinyl acetate, poly vinylchloride polystyrene and polyvinylpryrrolidone, derivatives thereof,linear and branched copolymers and block copolymers thereof, and blendsthereof. Exemplary biodegradable polymers include polyesters, poly(orthoesters), poly(ethylene imines), poly(caprolactones),poly(hydroxybutyrates), poly(hydroxyvalerates), polyanhydrides,poly(acrylic acids), polyglycolides, poly(urethanes), polycarbonates,polyphosphate esters, polyphosphazenes, derivatives thereof, linear andbranched copolymers and block copolymers thereof, and blends thereof. Inparticularly preferred embodiments the block copolymer containsbiodegradable polyesters or polyanhydrides such as poly(lactic acid),poly(glycolic acid), and poly(lactic-co-glycolic acid).

The block copolymers can have the structure X-PC, Y-PC, X-PC-Y,(X-PC)_(n), (X-PC)_(n)-Y, (X-PC-Y)_(n), or X-(PC-Y)_(n) where PC is apolycation block, X is a hydrophobic polymer block, Y is a hydrophilicpolymer block, and n is an integer from 2 to 10. One or more of thepolycation block, the hydrophobic polymer block, or the hydrophilicpolymer block can be biodegradable in whole or in part. In preferredembodiments X is an aliphatic polyester block such as poly(lactic acid),poly(glycolic acid), or poly(lactic acid-co-glycolic acid) having amolecular weight between 0.5 kDa and 500 kDa, preferably between 1 kDaand 100 kDa, preferably between 5 kDa and 50 kDa. In preferredembodiments Y is a hydrophilic polyalkylene glycol such as polyethyleneglycol or polypropylene glycol having a molecular weight between 0.5 kDaand 500 kDa, preferably between 1 kDa and 50 kDa, preferably between 1kDa and 20 kDa, between 1 kDa and 10 kDa, or between 3 kDa and 10 kDa.

The block copolymer can be a PLGA-PC block copolymer having thestructure

or a PLGA-PC-PEG block copolymer having the structure

where each R₁ is independently a substituted or unsubstituted alkyl,alkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl,heterocycloalkenyl, aryl, or heteroaryl; each R₂ is independently alinear or branched alkyl, alkenyl, cycloalkyl, heterocycloalkyl,cycloalkenyl, heterocycloalkenyl, aryl, or heteroaryl group substitutedwith one or more cationic primary, secondary, or tertiary amino groupsor quaternary ammonium, sulfonium or phosphinium groups; and x, y, n,and m are integers between 1 and 10,000, between 1 and 5,000, between 10and 1,000, or between 10 and 500. In some embodiments R₁ is asubstituted or unsubstituted alkyl, alkenyl, alkynyl, cycloalkyl,heterocycloalkyl, cycloalkenyl, heterocycloalkenyl, aryl, or heteroarylcontaining from 1 to 30 carbon atoms, from 1 to 20 carbon atoms, from 1to 12 carbon atoms, or from 2 to 10 carbon atoms. R₁ can be a linear orbranched alkyl, substituted alkyl, alkenyl, substituted alkenyl,alkylene oxide, or substituted alkylene oxide. Exemplary R₁ groupsinclude linear and branched alkyl and substituted alkyl, alkenyl, oralkylene oxide containing from 2 to 20, preferably from 2 to 12 carbonatoms. In preferred embodiments at least one R₂ is a cationichydrophilic side chain containing from 1 to 12 carbon atoms. Each R₂ canindependently be aliphatic amine, cycloaliphatic amine, heterocyclicamine or aromatic amine, provided that on at least one R₂ there is atleast one positively charged amine group in the side chain. Thepositively charged amine group can have a pKa greater than 5.0, greaterthan 7.0, greater than 9.0, greater than 11.0, greater than 11.5,greater than 12.0, or greater than 12.5. In some embodiments thepositively charged amine groups has a pKa between 5.0 and 12.5, between5.0 and 10.5, between 5.0 and 9.0, or between 6.0 and 8.0. R₂ can be theside chain of cationic amino acids such as lysine, arginine andhistidine, homolysine, ornithine, diaminobutyric acid, diaminopimelicacid, diaminopropionic acid and homoarginine as well as trimethylysineand trimethylornithine, 4-aminopiperidine-4-carboxylic acid,4-amino-1-carbamimidoylpiperidine-4-carboxylic acid and4-guanidinophenylalanine.

C. Conjugates

The polymer can include a conjugate of the polymers described above withone or more additional moieties. Conjugates can include the polycationsand the polycation containing block copolymers having end-to-endlinkages with additional moieties. The additional moiety can be atargeting moiety, a lipid, a protective group, a reactive couplinggroup, a detectable label, or a therapeutic, prophylactic, or diagnosticagent. For example, the conjugate can have the structure X-PC-Z orX-PC-Y-Z, where X, PC, and Y are as described above and Z is a targetingmoiety, a lipid, a protective group, a reactive coupling group, adetectable label, or a therapeutic, prophylactic, or diagnostic agent. Zcan be the end group of the polymer, e.g. Z can be a reactive couplinggroup such as —NH, —COOH, or —SH.

The targeting moiety may refer to elements that bind to or otherwiselocalize the nanoparticles to a specific locale. The locale may be atissue, a particular cell type, or a subcellular compartment. Thetargeting moiety can be an antibody or antigen binding fragment thereof,an aptamer, or a small molecule (less than 500 Daltons). The targetingmoiety may have an affinity for a cell-surface receptor or cell-surfaceantigen on a target cell and result in internalization of the particlewithin the target cell.

The conjugate can also contain a detectable label, such as, aradioisotope, a fluorophore (e.g., fluorescein isothiocyanate (FITC),phycoerythrin (PE)), an enzyme (e.g., alkaline phosphatase, horseradishperoxidase), element particles (e.g., gold particles) or a contrastagent. In other embodiments the label is a contrast agent. A contrastagent refers to a substance used to enhance the contrast of structuresor fluids within the body in medical imaging. Contrast agents are knownin the art and include, but are not limited to agents that work based onX-ray attenuation and magnetic resonance signal enhancement. Suitablecontrast agents include iodine and barium.

III. Particles

Particles are provided containing one or more of the polycations or oneor more of the polycation containing block copolymers described above.The particles can contain one or more anionic therapeutic, prophylactic,or diagnostic agents. The particles can be microparticles ornanoparticles, although nanoparticles are preferred. Representativenanoparticles contain a polycation or a polycation containing blockcopolymer and an anionic therapeutic, prophylactic, or diagnostic agent.

The nanoparticles may have any desired size for the intended use. Thenanoparticles may have any diameter from 10 nm to 1,000 nm. Thenanoparticle can have a diameter between 10 nm and 900 nm, between 10 nmand 800 nm, between 10 nm and 700 nm, between 10 nm and 600 nm, between10 nm and 500 nm, between 20 nm and 500 nm, between 30 nm and 500 nm,between 40 nm and 500 nm, between 50 nm and 500 nm, between 50 nm and400 nm, between 50 nm and 350 nm, between 50 nm and 300 nm, or between50 nm and 200 nm. In preferred embodiments the nanoparticles can have adiameter less than 400 nm, less than 300 nm, or more preferably lessthan 200 nm.

A. Polymers

The particles, including microparticles and nanoparticles, contain oneor more polycations or polycation containing copolymers as describedabove. The polycation or polycation containing copolymer can be presentwith additional polymers.

The particles can contain one more of the following polyesters:homopolymers including glycolic acid units, referred to herein as “PGA”,and lactic acid units, such as poly-L-lactic acid, poly-D-lactic acid,poly-D,L-lactic acid, poly-L-lactide, poly-D-lactide, andpoly-D,L-lactide, collectively referred to herein as “PLA”, andcaprolactone units, such as poly(ε-caprolactone), collectively referredto herein as “PCL”; and copolymers including lactic acid and glycolicacid units, such as various forms of poly(lactic acid-co-glycolic acid)and poly(lactide-co-glycolide) characterized by the ratio of lacticacid:glycolic acid, collectively referred to herein as “PLGA”; andpolyacrylates, and derivatives thereof. Exemplary polymers also includecopolymers of polyethylene glycol (PEG) and the aforementionedpolyesters, such as various forms of PLGA-PEG or PLA-PEG copolymers,collectively referred to herein as “PEGylated polymers”. In certainembodiments, the PEG region can be covalently associated with polymer toyield “PEGylated polymers” by a cleavable linker.

The particles can contain one or more hydrophilic polymers. Hydrophilicpolymers include cellulosic polymers such as starch and polysaccharides;hydrophilic polypeptides; poly(amino acids) such as poly-L-glutamic acid(PGS), gamma-polyglutamic acid, poly-L-aspartic acid, poly-L-serine, orpoly-L-lysine; polyalkylene glycols and polyalkylene oxides such aspolyethylene glycol (PEG), polypropylene glycol (PPG), and poly(ethyleneoxide) (PEO); poly(oxyethylated polyol); poly(olefinic alcohol);polyvinylpyrrolidone); poly(hydroxyalkylmethacrylamide);poly(hydroxyalkylmethacrylate); poly(saccharides); poly(hydroxy acids);poly(vinyl alcohol), and copolymers thereof.

The particles can contain one or more hydrophobic polymers.

Examples of suitable hydrophobic polymers include polyhydroxyacids suchas poly(lactic acid), poly(glycolic acid), and poly(lacticacid-co-glycolic acids); polyhydroxyalkanoates such aspoly3-hydroxybutyrate or poly4-hydroxybutyrate; polycaprolactones;poly(orthoesters); polyanhydrides; poly(phosphazenes);poly(lactide-co-caprolactones); polycarbonates such as tyrosinepolycarbonates; polyamides (including synthetic and natural polyamides),polypeptides, and poly(amino acids); polyesteramides; polyesters;poly(dioxanones); poly(alkylene alkylates); hydrophobic polyethers;polyurethanes; polyetheresters; polyacetals; polycyanoacrylates;polyacrylates; polymethylmethacrylates; polysiloxanes;poly(oxyethylene)/poly(oxypropylene) copolymers; polyketals;polyphosphates; polyhydroxyvalerates; polyalkylene oxalates;polyalkylene succinates; poly(maleic acids), as well as copolymersthereof.

In certain embodiments, the hydrophobic polymer is an aliphaticpolyester. In preferred embodiments, the hydrophobic polymer ispoly(lactic acid), poly(glycolic acid), or poly(lactic acid-co-glycolicacid).

The particles can contain one or more biodegradable polymers.Biodegradable polymers can include polymers that are insoluble orsparingly soluble in water that are converted chemically orenzymatically in the body into water-soluble materials. Biodegradablepolymers can include soluble polymers crosslinked by hydolyzablecross-linking groups to render the crosslinked polymer insoluble orsparingly soluble in water.

Biodegradable polymers in the particle can include polyamides,polycarbonates, polyalkylenes, polyalkylene glycols, polyalkyleneoxides, polyalkylene terepthalates, polyvinyl alcohols, polyvinylethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone,polyglycolides, polysiloxanes, polyurethanes and copolymers thereof,alkyl cellulose, hydroxyalkyl celluloses, cellulose ethers, celluloseesters, nitro celluloses, polymers of acrylic and methacrylic esters,methyl cellulose, ethyl cellulose, hydroxypropyl cellulose,hydroxy-propyl methyl cellulose, hydroxybutyl methyl cellulose,cellulose acetate, cellulose propionate, cellulose acetate butyrate,cellulose acetate phthalate, carboxylethyl cellulose, cellulosetriacetate, cellulose sulphate sodium salt, poly (methyl methacrylate),poly(ethylmethacrylate), poly(butylmethacrylate),poly(isobutylmethacrylate), poly(hexlmethacrylate),poly(isodecylmethacrylate), poly(lauryl methacrylate), poly (phenylmethacrylate), poly(methyl acrylate), poly(isopropyl acrylate),poly(isobutyl acrylate), poly(octadecyl acrylate), polyethylene,polypropylene poly(ethylene glycol), poly(ethylene oxide), poly(ethyleneterephthalate), poly(vinyl alcohols), poly(vinyl acetate, poly vinylchloride polystyrene and polyvinylpryrrolidone, derivatives thereof,linear and branched copolymers and block copolymers thereof, and blendsthereof. Exemplary biodegradable polymers include polyesters, poly(orthoesters), poly(ethylene imines), poly(caprolactones),poly(hydroxybutyrates), poly(hydroxyvalerates), polyanhydrides,poly(acrylic acids), polyglycolides, poly(urethanes), polycarbonates,polyphosphate esters, polyphosphazenes, derivatives thereof, linear andbranched copolymers and block copolymers thereof, and blends thereof. Inparticularly preferred embodiments the nanoparticle containsbiodegradable polyesters or polyanhydrides such as poly(lactic acid),poly(glycolic acid), and poly(lactic-co-glycolic acid).

The particles can contain one or more amphiphilic polymers. Amphiphilicpolymers can be polymers containing a hydrophobic polymer block and ahydrophilic polymer block. In some embodiments the amphiphilic polymeris a polycation containing copolymer as described above. The hydrophobicpolymer block can contain one or more of the hydrophobic polymers aboveor a derivative or copolymer thereof. The hydrophilic polymer block cancontain one or more of the hydrophilic polymers above, one or morepolycations above, or a derivative or copolymer thereof. In somepreferred embodiments the amphiphilic polymer is a di-block polymercontaining a hydrophobic end formed from a hydrophobic polymer and ahydrophilic end formed of a hydrophilic polymer. In some embodiments, amoiety can be attached to the hydrophobic end, to the hydrophilic end,or both. The amphiphilic polymer can be a tri-block copolymer containinga hydrophobic end formed of a hydrophobic polymer and a hydrophilic endformed of a polycation block and a hydrophilic polymer block. Thenanoparticle can contain two or more amphiphilic polymers. For example,the nanoparticle may contain an amphiphilic PLGA-PC block copolymer asdescribed above and a PLGA-PEG block copolymer.

In preferred embodiments the particles contain a first amphiphilicpolymer having a hydrophobic polymer block and a hydrophilic polymerblock containing a polycation, and a second amphiphilic polymer having ahydrophobic polymer block and a hydrophilic polymer block but withoutthe polycation. The hydrophobic polymer block of the first amphiphilicpolymer and the hydrophobic polymer block of the second amphiphilicpolymer may be the same or different. In other preferred embodiments theparticles contain a first polymer that is an amphiphilic polymer havinga hydrophobic polymer block and a hydrophilic polymer block containing apolycation, and a second polymer that is a hydrophobic polymer. Thehydrophobic polymer block of the first polymer and the hydrophobicpolymer of the second polymer may be the same or different.

B. Anionic Active Agents

The nanoparticles contain one or more exogenous anionic molecules, suchas a therapeutic, prophylactic, or diagnostic agent. The nanoparticlecan contain one or more proteins, peptides, or analogues thereof, one ormore nucleic acids, or a combination thereof. The nanoparticle cancontain one or more small molecule anionic active agents, one or morehigh molecular weight anionic active agents, or a combination thereof.

A protein can be, for example, a protein drug, an antibody, an antibodyfragment, a recombinant antibody, a recombinant protein, an enzyme, orthe like. Proteins can include DNA-binding proteins, transcriptionfactors, chromatin remodeling factors, methylated DNA binding proteins,polymerases, methylases, demethylases, acetylases, deacetylases,kinases, phosphatases, integrases, recombinases, ligases,topoisomerases, gyrases and helicases.

Anionic protein analogues can include anionic proteins withmodifications such as, for example, acetylation, phosphorylation andmyristylation, as well as those containing non-naturally-occurring aminoacids, amino acid variants and/or non-peptide inter-amino acid linkages.Modifications can include the addition of a chemical entity such as acarbohydrate group, a phosphate group, a farnesyl group, an isofarnesylgroup, a fatty acid group, a linker for conjugation, functionalization,or other modification, etc.

Nucleic acids can include RNA, DNA; synthetic or semi-syntheticderivatives of DNA and RNA, cDNA, or nucleic acid analogs such asphosphorothioates, phosphoramidates, or phosphonates analogs, anti-senseRNA, plasmid DNA. Nucleic acids can be single- or double-stranded; canbe linear, branched or circular; and can be of any length. Nucleic acidscan include modified bases, sugars and/or mternucleotide linkages.Nucleic acid analogues include polyamide (peptide) nucleic acids andchimeric molecules comprising PNA and/or DNA and/or RNA. Nucleic acidsinclude those capable of forming duplexes and those capable of formingtriplex structures with double-stranded DNA.

C. Outer Layer

The particles can contain one or more out layers. The outer layer(s) canstabilize the particles against degradation or providestealth-properties to avoid immune detection and increase circulationhalf-life. The outer layer can include one or more of a biodegradablepolymer, a stealth polymer, a lipid, a surfactant, or a polymer-lipidconjugate. The protective layer can be present in an amount between 1%and 60%, between 1% and 50%, between 1% and 30%, or between 1% and 20%(w/w) based upon the weight of the particle.

The biodegradable polymer can be any of the biodegradable polymersdescribed above. Preferred biodegradable polymers include hydrophilicpolyesters, poly(ortho esters), poly(ethylene imines),poly(caprolactones), poly(hydroxybutyrates), poly(hydroxyvalerates),polyanhydrides, poly(acrylic acids), and polyglycolides.

The stealth polymer can include homo polymers or copolymers ofpolyalkene glycols, such as poly(ethylene glycol), poly(propyleneglycol), poly(butylene glycol), and may include acrylates andacrylamide, such as hydroxyethyl methacrylate andhydroxypropylmethacrylamide respectively. In preferred embodiments thestealth polymer is poly(ethylene glycol).

The lipid can be any synthetic or naturally derived lipid. In preferredembodiments the lipid is an amphiphilic lipid such as phospholipids,phosphoric acid esters, galactolipids, sphingomyelin (sphingolipids),galactose fat, sugar-based ester and/or phosphatidylcholine base. Thelipid can be a phospholipid, such as 1,2distearoyl-sn-glycero-3-phosphoethanolamine (DSPE),dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine(DSPC), diarachidoylphosphatidylcholine (DAPC),dibehenoylphosphatidylcholine (DBPC), ditricosanoylphosphatidylcholine(DTPC), and dilignoceroylphatidylcholine (DLPC). Phospholipids which maybe used include, but are not limited to, phosphatidic acids,phosphatidyl cholines with both saturated and unsaturated lipids,phosphatidyl ethanolamines, phosphatidylglycerols, phosphatidylserines,phosphatidylinositols, lysophosphatidyl derivatives, cardiolipin, andβ-acyl-γ-alkyl phospholipids. Examples of phospholipids include, but arenot limited to, phosphatidylcholines such asdioleoylphosphatidylcholine, dimyristoylphosphatidylcholine,dipentadecanoylphosphatidylcholine dilauroylphosphatidylcholine,dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine(DSPC), diarachidoylphosphatidylcholine (DAPC),dibehenoylphosphatidylcho-line (DBPC), ditricosanoylphosphatidylcholine(DTPC), dilignoceroylphatidylcholine (DLPC); andphosphatidylethanolamines such as dioleoylphosphatidylethanolamine or1-hexadecyl-2-palmitoylglycerophos-phoethanolamine. Syntheticphospholipids with asymmetric acyl chains (e.g., with one acyl chain of6 carbons and another acyl chain of 12 carbons) may also be used. Insome embodiments the lipid is lecithin. Lecithin has an advantage ofbeing a natural lipid that is available from, e.g., soybean, and alreadyhas FDA approval for use in other delivery devices. In addition, amixture of lipids such as lethicin is more advantageous than one singlepure lipid. The amphiphilic lipid can have a molecular weight between200 g/mol and 1,000 g/mol, e.g., 700-900 g/mol.

Suitable surfactants may include anionic, cationic, amphoteric ornonionic surfactants. Suitable anionic surfactants include, but are notlimited to, those containing carboxylate, sulfonate and sulfate ions.Examples of anionic surfactants include sodium, potassium, ammonium oflong chain alkyl sulfonates and alkyl aryl sulfonates such as sodiumdodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodiumdodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodiumbis-(2-ethylthioxyl)-sulfosuccinate; and alkyl sulfates such as sodiumlauryl sulfate. Cationic surfactants include, but are not limited to,quaternary ammonium compounds such as benzalkonium chloride,benzethonium chloride, cetrimonium bromide, stearyl dimethylbenzylammonium chloride, polyoxyethylene and coconut amine. Examples ofnonionic surfactants include ethylene glycol monostearate, propyleneglycol myristate, glyceryl monostearate, glyceryl stearate,polyglyceryl-4-oleate, sorbitan acylate, sucrose acylate, PEG-150laurate, PEG-400 monolaurate, polyoxyethylene monolaurate, polysorbates,polyoxyethylene octylphenylether, PEG-1000 cetyl ether, polyoxyethylenetridecyl ether, polypropylene glycol butyl ether, Poloxamer® 401,stearoyl monoisopropanolamide, and polyoxyethylene hydrogenated tallowamide. Examples of amphoteric surfactants include sodiumN-dodecyl-β-alanine, sodium N-lauryl-β-iminodipropionate,myristoamphoacetate, lauryl betaine and lauryl sulfobetaine.

A polymer-lipid conjugate can include end-to-end linkages between alipid, such as those described above, and a polymer, including abiodegradable polymer and/or a stealth polymer. In preferred embodimentsthe polymer-lipid conjugate is a PEG-lipid conjugate. PEG-lipidconjugates include, but are not limited to, PEG coupled todialkyloxypropyls, PEG coupled to diacylglycerols (DAG), PEG coupled tocholesterol, PEG coupled to phosphatidylethanolamines, PEG conjugated toceramides (see, e.g., U.S. Pat. No. 5,885,613); cationic PEG lipids;cationic-polymer-lipid conjugates (CPLs). Examples of PEG-modifiedlipids include PEG-modified phosphatidylethanolamine and phosphatidicacid, PEG-ceramide conjugates {e.g., PEG-CerC14 or PEG-CerC20) which aredescribed in copending U.S. Ser. No. 08/486,214, incorporated herein byreference, PEG-modified dialkylamines and PEG-modified1,2-diacyloxypropan-3-amines. Particularly preferred are PEG-modifieddiacylglycerols and dialkylglycerols. In one embodiment, the PEG-lipidconjugate is 3-N-[(-methoxypoly(ethyleneglycol)2000)carbamoyl]-1,2-dimyristyloxy-propylamine (PEG-DMG).PEG-lipid conjugates are also described, e.g., in U.S. Pat. Nos.5,820,873, 5,534,499 and 5,885,613.

D. Cationic Particle Core

The nanoparticles in some embodiments contain a cationic particle core.The cationic particle core contains one or more polycations orpolycation containing copolymers described above. The cationic polymercore can also contain one or more additional polymers including thehydrophobic, hydrophilic, and biodegradable polymers described above.

The cationic particle core can be used to form the various core-shellnanoparticles (see FIGS. 4A-4D for examples) and multi-core shellnanoparticles (see FIG. 5) described below. In preferred embodiments thecationic polymer core contains a block copolymer having a hydrophobicpolymer block and a hydrophilic polycation block, e.g. the PLGA-PC blockcopolymers described above. The cationic particle core can have acore-shell structure with a hydrophobic inner region containinghydrophobic polymer and a charged outer region containing the polycationor polycation block.

The cationic particle core can contain a mixture of 2, 3, 4, or morepolymers. In preferred embodiments the cationic polymer core contains ablock copolymer having a hydrophobic polymer block and a hydrophilicpolycation block and a second polymer containing the hydrophobic polymerwithout the polycation block. For example, the cationic particle corecan contain a PLGA-PC block copolymer and a PLGA homopolymer. See FIGS.4A-4E. The properties of the cationic particle core, including theparticle size and surface zeta potential can be modified by varying thelength of the PC or PLGA chain in the copolymer, by changing the ratioof PLGA-PC to PLGA homopolymer, by changing the structure of thepolycation polymer, or a combination thereof.

The cationic particle core can have any diameter from about 1 nm toabout 300 nm, although in preferred embodiments the cationic particlecore has a diameter between 10 nm and 300 nm, between 10 nm and 100 nm,between 20 nm and 80 nm, or between 20 nm and 40 nm. The cationicparticle core can have a large surface zeta potential of greater than+10 mV, greater than +20 mV, greater than +30 mV, or greater than +40mV. The cationic particle cores can have a surface zeta potential valuebetween 0 and +100 mV, between +5 mV and +80 mV, between +10 mV and +60mV, or between +15 mV and +50 mV.

E. Core-Shell Nanoparticles

Nanoparticles are provided having various core-shell structures. Inpreferred embodiments the nanoparticles contain a cationic polymer coreas described above in combination with the anionic active agent,optionally including protective layers described above. The strongelectrostatic interactions between the cationic particle core and theanionic active agent provide strong physical adsorption of the anionicactive agents around the cationic particle core. The particle thus formsa core-shell structure with the cationic particle core surrounded by athick layer of the anionic active agents. The anionic active agents canform a layer around the cationic particle core having a thickness up toabout 1 micron, 800 nm, 600 nm, 500 nm, 250 nm, 100 nm, 75 nm, 50 nm, 40nm, 30 nm, or up to about 20 nm.

The core-shell nanoparticles can contain a lipid monolayer (e.g. FIG.4A) or lipid bilayer (e.g. FIG. 4B) shell. Exemplary embodiments providea core-shell nanoparticle having (1) a cationic particle core; (2) anouter lipid layer; and (3) a layer of anionic active agent dispersedbetween the cationic particle core and the lipid layer. Additionalmoieties such as targeting moieties can be attached to the exteriorsurface of the lipid.

The core-shell nanoparticles can contain a polymer-lipid conjugate (e.g.FIG. 4C). Exemplary embodiments provide a core-shell nanoparticle having(1) a cationic particle core; (2) a layer containing a polymer-lipidconjugate; and (3) a layer of anionic active agent dispersed between thecationic particle core and the polymer-lipid conjugate layer. Additionalmoieties such as targeting moieties can be attached to the exteriorsurface, e.g. attached covalently or non-covalently to the polymer-lipidconjugate. For example a core-shell particle is provided containing (1)a cationic particle core containing a blend of PLGA and ablock-copolymer having the structure PLGA-PC where PC is a polycationpolymer described above; (2) a layer of a Z-PEG-lipid conjugate where Zis a targeting moiety targeting a specific tissue, cell type orsubcellular; and (3) a layer of anionic active agent dispersed betweenthe cationic particle core and the Z-PEG-lipid conjugate layer.

Core-shell nanoparticles can contain an outer polymer layer that can bea biodegradable polymer layer, a stealth polymer layer, or both (e.g.FIG. 4D and FIG. 4E). For example, a core-shell particle can have (1) acationic particle core; (2) a layer containing a biodegradable polymer;and (3) a layer of anionic active agent dispersed between the cationicparticle core and the biodegradable polymer layer. The biodegradablepolymer layer can contain one or a mixture of 2, 3, 4, or more polymers.The biodegradable polymer layer can contain any biodegradable andbiocompatible polymer. The biodegradable polymer layer can contain ahydrophobic polymer, a hydrophilic polymer, or copolymers thereof. Inpreferred embodiments the core-shell particle contains (1) a cationicparticle core; (2) a layer containing an amphiphilic copolymer having ahydrophobic polymer block and a hydrophilic polymer block; and (3) alayer of anionic active agent dispersed between the cationic particlecore and the amphiphilic polymer layer.

D. Multi-Core-Shell Nanoparticles

Multi-core shell nanoparticles are also provided. The multi-core shellnanoparticles contain 2, 3, 4, or more cationic nanoparticle cores incombination with the anionic active agent, optionally containing aprotective layer. In one embodiment a multi-core shell nanoparticle isprovided having 3 cationic particle cores dispersed throughout andencompassed within the anionic active agents, optionally containingadditional excipients or stabilizers, for example, as depicted in FIG.5. The multi-core shell nanoparticle may have any diameter up to about 1micron, although smaller particles are preferred. In some embodimentsthe multi-core shell nanoparticles have a diameter between 20 nm and1,000 nm, between 20 nm and 800 nm, between 50 nm and 500 nm, between 50nm and 400 nm, between 50 nm and 300 nm, between 100 nm and 220 nm, orbetween 100 nm and 200 nm.

The multi-core shell nanoparticles may contain any number of cationicparticle cores, e.g. between 2 and 100, between 2 and 50, between 2 and10, or between 2 and 5. The multi-core shell nanoparticle can contain 2,3, 4, or more cationic particle cores.

Multi-core shell nanoparticles are provided containing (1) a pluralityof cationic particle cores and (2) a layer of anionic active agentsencapsulating the cationic particle cores. The cationic particle coresare distributed within the interior of the multi-core shellnanoparticle. The multi-core shell nanoparticle can contain a protectivelayer surrounding the anionic active agents, e.g. lipid monolayers orbilayers, polymer-lipid conjugate layers, and/or biodegradable polymerlayers.

Exemplary embodiments provide a core-shell nanoparticle having (1) aplurality of cationic particle cores encapsulated by and dispersedwithin a plurality of anionic active agents to form a particle and (2) aprotective outer layer. The protective outer layer can be a lipidmonolayer, a lipid bilayer, a polymer-lipid conjugate layer, or abiodegradable polymer layer. Additional moieties such as targetingmoieties can be attached to the exterior surface, e.g. attachedcovalently or non-covalently to the lipid, polymer, or polymer-lipidconjugate.

An exemplary embodiment provides a multi-core-shell nanoparticlecontaining a plurality of cationic particle cores encapsulated by anddispersed within a plurality of anionic active agents to form aparticle, where the cationic particle cores contain a blend of PLGA anda block-copolymer having the structure PLGA-PC where PC is a polycationpolymer described above.

IV. Formulations

The formulations described herein contain an effective amount of theparticles in a pharmaceutical carrier appropriate for administration toan individual in need thereof. In some embodiments the formulationscontain nanoparticles. The formulations can be administered parenterally(e.g., by injection or infusion), enterally, topically (e.g., to theeye), or via pulmonary administration.

A. Parenteral Formulations

The nanoparticles can be formulated for parenteral delivery, such asinjection or infusion, in the form of a solution or suspension. Theformulation can be administered via any route, such as, the blood streamor directly to the organ or tissue to be treated.

Parenteral formulations can be prepared as aqueous compositions usingtechniques is known in the art. Typically, such compositions can beprepared as injectable formulations, for example, solutions orsuspensions; solid forms suitable for using to prepare solutions orsuspensions upon the addition of a reconstitution medium prior toinjection; emulsions, such as water-in-oil (w/o) emulsions, oil-in-water(o/w) emulsions, and microemulsions thereof, liposomes, or emulsomes.

The carrier can be a solvent or dispersion medium containing, forexample, water, ethanol, one or more polyols (e.g., glycerol, propyleneglycol, and liquid polyethylene glycol), oils, such as vegetable oils(e.g., peanut oil, corn oil, sesame oil, etc.), and combinationsthereof. The proper fluidity can be maintained, for example, by the useof a coating, such as lecithin, by the maintenance of the requiredparticle size in the case of dispersion and/or by the use ofsurfactants. In many cases, it will be preferable to include isotonicagents, for example, sugars or sodium chloride.

Solutions and dispersions of the nanoparticles can be prepared in wateror another solvent or dispersing medium suitably mixed with one or morepharmaceutically acceptable excipients including, but not limited to,surfactants, dispersants, emulsifiers, pH modifying agents, andcombination thereof.

Suitable surfactants may be anionic, cationic, amphoteric or nonionicsurface active agents. Suitable anionic surfactants include, but are notlimited to, those containing carboxylate, sulfonate and sulfate ions.Examples of anionic surfactants include sodium, potassium, ammonium oflong chain alkyl sulfonates and alkyl aryl sulfonates such as sodiumdodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodiumdodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodiumbis-(2-ethylthioxyl)-sulfosuccinate; and alkyl sulfates such as sodiumlauryl sulfate. Cationic surfactants include, but are not limited to,quaternary ammonium compounds such as benzalkonium chloride,benzethonium chloride, cetrimonium bromide, stearyl dimethylbenzylammonium chloride, polyoxyethylene and coconut amine. Examples ofnonionic surfactants include ethylene glycol monostearate, propyleneglycol myristate, glyceryl monostearate, glyceryl stearate,polyglyceryl-4-oleate, sorbitan acylate, sucrose acylate, PEG-150laurate, PEG-400 monolaurate, polyoxyethylene monolaurate, polysorbates,polyoxyethylene octylphenylether, PEG-1000 cetyl ether, polyoxyethylenetridecyl ether, polypropylene glycol butyl ether, Poloxamer® 401,stearoyl monoisopropanolamide, and polyoxyethylene hydrogenated tallowamide. Examples of amphoteric surfactants include sodiumN-dodecyl-β-alanine, sodium N-lauryl-β-iminodipropionate,myristoamphoacetate, lauryl betaine and lauryl sulfobetaine.

The formulation can contain a preservative to prevent the growth ofmicroorganisms. Suitable preservatives include, but are not limited to,parabens, chlorobutanol, phenol, sorbic acid, and thimerosal. Theformulation may also contain an antioxidant to prevent degradation ofthe active agent(s) or nanoparticles.

The formulation is typically buffered to a pH of 3-8 for parenteraladministration upon reconstitution. Suitable buffers include, but arenot limited to, phosphate buffers, acetate buffers, and citrate buffers.

Water soluble polymers are often used in formulations for parenteraladministration. Suitable water-soluble polymers include, but are notlimited to, polyvinylpyrrolidone, dextran, carboxymethylcellulose, andpolyethylene glycol.

Sterile injectable solutions can be prepared by incorporating thenanoparticles in the required amount in the appropriate solvent ordispersion medium with one or more of the excipients listed above, asrequired, followed by filtered sterilization. Generally, dispersions areprepared by incorporating the various sterilized nanoparticles into asterile vehicle which contains the basic dispersion medium and therequired other ingredients from those listed above. In the case ofsterile powders for the preparation of sterile injectable solutions, thepreferred methods of preparation are vacuum-drying and freeze-dryingtechniques which yield a powder of the nanoparticle plus any additionaldesired ingredient from a previously sterile-filtered solution thereof.The powders can be prepared in such a manner that the particles areporous in nature, which can increase dissolution of the particles.Methods for making porous particles are well known in the art.

Pharmaceutical formulations for parenteral administration are preferablyin the form of a sterile aqueous solution or suspension of particlesformed from one or more polymer-drug conjugates. Acceptable solventsinclude, for example, water, Ringer's solution, phosphate bufferedsaline (PBS), and isotonic sodium chloride solution. The formulation mayalso be a sterile solution, suspension, or emulsion in a nontoxic,parenterally acceptable diluent or solvent such as 1,3-butanediol.

In some instances, the formulation is distributed or packaged in aliquid form. Alternatively, formulations for parenteral administrationcan be packed as a solid, obtained, for example by lyophilization of asuitable liquid formulation. The solid can be reconstituted with anappropriate carrier or diluent prior to administration.

Solutions, suspensions, or emulsions for parenteral administration maybe buffered with an effective amount of buffer necessary to maintain apH suitable for ocular administration. Suitable buffers are well knownby those skilled in the art and some examples of useful buffers areacetate, borate, carbonate, citrate, and phosphate buffers.

Solutions, suspensions, or emulsions for parenteral administration mayalso contain one or more tonicity agents to adjust the isotonic range ofthe formulation. Suitable tonicity agents are well known in the art andsome examples include glycerin, mannitol, sorbitol, sodium chloride, andother electrolytes.

Solutions, suspensions, or emulsions for parenteral administration mayalso contain one or more preservatives to prevent bacterialcontamination of the ophthalmic preparations. Suitable preservatives areknown in the art, and include polyhexamethylenebiguanidine (PHMB),benzalkonium chloride (BAK), stabilized oxychloro complexes (otherwiseknown as PURITE®), phenylmercuric acetate, chlorobutanol, sorbic acid,chlorhexidine, benzyl alcohol, parabens, thimerosal, and mixturesthereof. Solutions, suspensions, or emulsions for parenteraladministration may also contain one or more excipients known art, suchas dispersing agents, wetting agents, and suspending agents.

B. Topical Formulations

The nanoparticles can be formulated for topical administration. Suitabledosage forms for topical administration include creams, ointments,salves, sprays, gels, lotions, emulsions, liquids, and transdermalpatches. The formulation may be formulated for transmucosal,transepithelial, transendothelial, or transdermal administration. Thecompositions contain one or more chemical penetration enhancers,membrane permeability agents, membrane transport agents, emollients,surfactants, stabilizers, and combination thereof.

In some embodiments, the nanoparticles can be administered as a liquidformulation, such as a solution or suspension, a semi-solid formulation,such as a lotion or ointment, or a solid formulation. In someembodiments, the nanoparticles are formulated as liquids, includingsolutions and suspensions, such as eye drops or as a semi-solidformulation, such as ointment or lotion for topical application to theskin, to the mucosa, such as the eye or vaginally or rectally.

The formulation may contain one or more excipients, such as emollients,surfactants, emulsifiers, and penetration enhancers.

C. Enteral Formulations

The nanoparticles can be prepared in enteral formulations, such as fororal administration. Suitable oral dosage forms include tablets,capsules, solutions, suspensions, syrups, and lozenges. Tablets can bemade using compression or molding techniques well known in the art.Gelatin or non-gelatin capsules can prepared as hard or soft capsuleshells, which can encapsulate liquid, solid, and semi-solid fillmaterials, using techniques well known in the art.

D. Pulmonary Formulations

The nanoparticle can be prepared for pulmonary administration. Thenanoparticles may be alone or in combination with additional activeagents, pharmaceutically acceptable carriers, pharmaceuticallyacceptable excipients, or combinations thereof. The pharmaceuticalcarrier and excipient are composed of materials that are considered safeand effective and may be administered to an individual without causingundesirable biological side effects or unwanted interactions.

Formulations for pulmonary administration can be administered usingmethods known in the art. Suitable methods can include, but are notlimited to, dry powder inhalers, pressurized metered-dose inhalers,nebulizers and aerosolizers, electrodynamic aerosol generators, andendotracheal aerosol generators.

In the case of pulmonary administration, formulations can be dividedinto dry powder formulations and liquid formulations. Both dry powderand liquid formulations can be used to form aerosol formulations. Usefulformulations, and methods of manufacture, are described by Caryalho, etal., J Aerosol Med Pulm Drug Deliv. 2011 April; 24(2):61-80. Epub 2011Mar. 16, for delivery of chemotherapeutic drugs to the lungs.

Dry Powder Formulations

Dry powder formulations are finely divided solid formulations containingone or more nanoparticles which are suitable for pulmonaryadministration. Dry powder formulations include one or morenanoparticles. Such dry powder formulations can be administered viapulmonary inhalation to a patient without the benefit of any carrier,other than air or a suitable propellant. Preferably, however, the drypowder formulations contain one or more nanoparticles in combinationwith a pharmaceutically acceptable carrier.

The pharmaceutical carrier may include a bulking agent, such ascarbohydrates (including monosaccharides, polysaccharides, andcyclodextrins), polypeptides, amino acids, and combinations thereof.Suitable bulking agents include fructose, galactose, glucose, lactitol,lactose, maltitol, maltose, mannitol, melezitose, myoinositol,50ryptococc, raffinose, stachyose, sucrose, trehalose, xylitol, hydratesthereof, and combinations thereof.

The pharmaceutical carrier may include a lipid or surfactant. Naturalsurfactants such as dipalmitoylphosphatidylcholine (DPPC) are the mostpreferred. This is commercially available for treatment of respiratorydistress syndrome in premature infants. Synthetic and animal derivedpulmonary surfactants include: Synthetic Pulmonary Surfactants such asEXOSURF® (a mixture of DPPC with hexadecanol and tyloxapol added asspreading agents); PUMACTANT® (Artificial Lung Expanding Compound orALEC®); a mixture of DPPC and PG; KL-4 (composed of DPPC,palmitoyl-oleoyl phosphatidylglycerol, and palmitic acid, combined witha 21 amino acid synthetic peptide that mimics the structuralcharacteristics of SP-B); and VENTICUTE® (DPPC, PG, palmitic acid andrecombinant SP-C) or animal derived surfactants such as ALVEOFACT®(extracted from cow lung lavage fluid); CUROSURF® (extracted frommaterial derived from minced pig lung; INFASURF® (extracted from calflung lavage fluid); and SURVANTA® (extracted from minced cow lung withadditional DPPC, palmitic acid and tripalmitin). EXOSURF®, CUROSURF®,INFASURF®, and SURVANTA® are the surfactants currently FDA approved foruse in the U.S.

The pharmaceutical carrier may also include one or more stabilizingagents or dispersing agents. The pharmaceutical carrier may also includeone or more pH adjusters or buffers. Suitable buffers include organicsalts prepared from organic acids and bases, such as sodium citrate orsodium ascorbate. The pharmaceutical carrier may also include one ormore salts, such as sodium chloride or potassium chloride.

Dry powder formulations are typically prepared by blending the one ormore nanoparticles with a pharmaceutical carrier. Optionally, additionalactive agents may be incorporated into the mixture as discussed above.The mixture is then formed into particles suitable for pulmonaryadministration using techniques known in the art, such aslyophilization, spray drying, agglomeration, spray coating, extrusionprocesses, hot melt particle formation, phase separation particleformation (spontaneous emulsion particle formation, solvent evaporationparticle formation, and solvent removal particle formation),coacervation, low temperature casting, grinding, milling (e.g.,air-attrition milling (jet milling), ball milling), high pressurehomogenization, and/or supercritical fluid crystallization.

An appropriate method of particle formation can be selected based on thedesired particle size, particle size distribution, and particlemorphology. In some cases, the method of particle formation is selectedso as to produce a population of particles with the desired particlesize, particle size distribution for pulmonary administration.Alternatively, the method of particle formation can produce a populationof particles from which a population of particles with the desiredparticle size, particle size distribution for pulmonary administrationis isolated, for example by sieving.

Liquid Formulations

Liquid formulations contain one or more nanoparticles, possibly with oneor more additional active agents, dissolved or suspended in a liquidpharmaceutical carrier.

Suitable liquid carriers include, but are not limited to distilledwater, de-ionized water, pure or ultrapure water, saline, and otherphysiologically acceptable aqueous solutions containing salts and/orbuffers, such as phosphate buffered saline (PBS), Ringer's solution, andisotonic sodium chloride, or any other aqueous solution acceptable foradministration to an animal or human.

Preferably, liquid formulations are isotonic relative to physiologicalfluids and of approximately the same pH, ranging e.g., from about pH 4.0to about pH 7.4, more preferably from about pH 6.0 to pH 7.0. The liquidpharmaceutical carrier can include one or more physiologicallycompatible buffers, such as a phosphate buffers. One skilled in the artcan readily determine a suitable saline content and pH for an aqueoussolution for pulmonary administration.

Liquid formulations may include one or more suspending agents, such ascellulose derivatives, sodium alginate, polyvinylpyrrolidone, gumtragacanth, or lecithin. Liquid formulations may also include one ormore preservatives, such as ethyl or n-propyl p-hydroxybenzoate.

In some cases the liquid formulation may contain one or more solventsthat are low toxicity organic (i.e. nonaqueous) class 3 residualsolvents, such as ethanol, acetone, ethyl acetate, tetrahydofuran, ethylether, and propanol. These solvents can be selected based on theirability to readily aerosolize the formulation. Any such solvent includedin the liquid formulation should not detrimentally react with the one ormore active agents present in the liquid formulation. The solvent shouldbe sufficiently volatile to enable formation of an aerosol of thesolution or suspension. Additional solvents or aerosolizing agents, suchas an alcohol, glycol, polyglycol, or fatty acid, can also be includedin the liquid formulation as desired to increase the volatility and/oralter the aerosolizing behavior of the solution or suspension.

Liquid formulations may also contain minor amounts of polymers,surfactants, or other excipients well known to those of the art. In thecontext of pulmonary formulations, “minor amounts” means no excipientsare present that might adversely affect uptake of the one or more activeagents in the lungs.

Aerosol Formulations

The dry powder and liquid formulations described above can be used toform aerosol formulations for pulmonary administration. Aerosols for thedelivery of therapeutic agents to the respiratory tract are known in theart. The term aerosol as used herein refers to any preparation of a finemist of solid or liquid particles suspended in a gas. In some cases, thegas may be a propellant; however, this is not required. Aerosols may beproduced using a number of standard techniques, including asultrasonication or high pressure treatment. Preferably, a dry powder orliquid formulation as described above is formulated into aerosolformulations using one or more propellants.

V. Methods of Making Polymers

Methods of polymer synthesis are described, for instance, in Braun etal. (2005) Polymer Synthesis: Theory and Practice. New York, N.Y.:Springer. The polymers may be synthesized via step-growthpolymerization, chain-growth polymerization, or plasma polymerization.

A. Methods of Making Polycations

Methods of making polycations containing the structural formuladescribed above are well known in the art and as described herein. Forexample, in some embodiments a polycation containing an α-amino acid canbe obtained by converting the α-amino acid into a bis-(α-amino acid)diester monomer, for example, by condensing the α-amino acid with adiol. As a result, ester bonds are formed. Then, the bis-(α-amino acid)diester is reacted by a polycondensation reaction with a di-acid, suchas sebacic acid, to obtain the final co-polymer having both ester andamide bonds. Alternatively, instead of the di-acid, an activated di-acidderivative, e.g., a bis-(p-nitrophenyl) diester, can be used as anactivated di-acid.

B. Methods of Making Copolymers

In some embodiments an block copolymer or amphiphilic block copolymer issynthesized starting from a hydrophobic polymer terminated with a firstreactive coupling group and a hydrophilic polymer terminated with asecond reactive coupling group capable of reacting with the firstreactive coupling group to form a covalent bond. The hydrophilicpolymer, hydrophobic polymer, or both can be a polycation or apolycation containing polymer. One of either the first reactive couplinggroup or the second reactive coupling group can be a primary amine,where the other reactive coupling group can be an amine-reactive linkinggroup such as isothiocyanates, isocyanates, acyl azides, NHS esters,sulfonyl chlorides, aldehydes, glyoxals, epoxides, oxiranes, carbonates,aryl halides, imidoesters, carbodiimides, anhydrides, and fluorophenylesters. One of either the first reactive coupling group or the secondreactive coupling group can be an aldehyde, where the other reactivecoupling group can be an aldehyde reactive linking group such ashydrazides, alkoxyamines, and primary amines. One of either the firstreactive coupling group or the second reactive coupling group can be athiol, where the other reactive coupling group can be a sulfhydrylreactive group such as maleimides, haloacetyls, and pyridyl disulfides.

In preferred embodiments a hydrophobic polymer terminated with an amineor an amine-reactive linking group is coupled to a hydrophilic polymeror a polycation polymer terminated with complimentary reactive linkinggroup. For example, an NHS ester activated PLGA can be formed byreacting PLGA-CO(OH) with NHS and a coupling reagent such asdicyclohexylcarbodiimide (DCC) or ethyl(dimethylaminopropyl)carbodiimide (EDC). The NHS ester activated PLGA can be reacted with ahydrophilic polymer or a polycation polymer terminated with a primaryamine, such as a PEG-NH₂ or PC-NH₂ to form an amphiphilic PLGA-b-PEG ora PLGA-b-PC block copolymer respectively.

In some embodiments a conjugate of an amphiphilic polymer with atargeting moiety is formed using the same or similar coupling reactions.In some embodiments the conjugate is made starting from a hydrophilicpolymer terminated on one end with a first reactive coupling group andterminated on a second end with a protective group. The hydrophilicpolymer is reacted with a targeting moiety having a reactive group thatis complimentary to the first reactive group to form a covalent bondbetween the hydrophilic polymer and the targeting moiety. The protectivegroup can then be removed to provide a second reactive coupling group,for example to allow coupling of a hydrophobic polymer block to theconjugate of the hydrophilic polymer with the targeting moiety. Ahydrophobic polymer terminated with a reactive coupling groupcomplimentary to the second reactive coupling group can then becovalently coupled to form the conjugate. Of course, the steps couldalso be performed in reverse order, i.e. a conjugate of a hydrophobicpolymer and a hydrophilic polymer could be formed first followed bydeprotection and coupling of the targeting moiety to the hydrophilicpolymer block.

In some embodiments a conjugate is formed having a moiety conjugated toboth ends of the amphiphilic polymer. For example, an amphiphilicpolymer having a hydrophobic polymer block and a hydrophilic polymerblock may have targeting moiety conjugated to the hydrophilic polymerblock and an additional moiety conjugated to the hydrophobic polymerblock. In some embodiments the additional moiety can be a detectablelabel. In some embodiments the additional moiety is a therapeutic,prophylactic, or diagnostic agent. For example, the additional moietycould be a moiety used for radiotherapy. The conjugate can be preparedstarting from a hydrophobic polymer having on one end a first reactivecoupling group and a another end first protective group and ahydrophilic polymer having on one end a second reactive coupling groupand on another end a second protective group. The hydrophobic polymercan be reacted with the additional moiety having a reactive couplinggroup complimentary to the first reactive coupling group, therebyforming a conjugate of the hydrophobic polymer to the additional moiety.The hydrophilic polymer can be reacted with a targeting moiety having areactive coupling group complimentary to the second reactive couplinggroup, thereby forming a conjugate of the hydrophilic polymer to thetargeting moiety. The first protective group and the second protectivegroup can be removed to yield a pair of complimentary reactive couplinggroups that can be reacted to covalently link the hydrophobic polymerblock to the hydrophilic polymer block.

VI. Methods of Making Polycation Containing Nanoparticles

A. Emulsion Methods

In some embodiments, a nanoparticle is prepared using an emulsionsolvent evaporation method. For example, a polymeric material isdissolved in a water immiscible organic solvent and mixed with a drugsolution or a combination of drug solutions. In some embodiments asolution of a therapeutic, prophylactic, or diagnostic agent to beencapsulated is mixed with the polymer solution. The polymer can be, butis not limited to, one or more of the following: PLA, PGA, PCL, theircopolymers, polyacrylates, the aforementioned PEGylated polymers, theaforementioned Polymer-drug conjugates, the aforementionedpolymer-peptide conjugates, or the aforementioned fluorescently labeledpolymers, or various forms of their combinations. The drug molecules canbe, but are not limited to, one or a more of the following: PPARgammaactivators (e.g. Rosiglitazone,(RS)-5-[4-(2-[methyl(pyridin-2-yl)amino]ethoxy)benzyl]thiazolidine-2,4-dione,Pioglitazone,(RS)-5-(4-[2-(5-ethylpyridin-2-yl)ethoxy]benzyl)thiazolidine-2,4-dione,Troglitazone,(RS)-5-(4-[(6-hydroxy-2,5,7,8-tetramethylchroman-2-yl)methoxy]benzyl)thiazolidine-2,4-dioneetc.), prostagladin E2 analog (PGE2,(5Z,11α,13E,15S)-7-[3-hydroxy-2-(3-hydroxyoct-1-enyl)-5-oxo-cyclopentyl]hept-5-enoicacid etc.), beta3 adrenoceptor agonist (CL 316243, Disodium5-[(2R)-2-[[(2R)-2-(3-Chlorophenyl)-2-hydroxyethyl]amino]propyl]-1,3-benzodioxole-2,2-dicarboxylatehydrate, etc.), Fibroblast Growth Factor 21 (FGF-21), Irisin, RNA, DNA,chemotherapeutic compounds, nuclear magnetic resonance (NMR) contrastagents, or combinations thereof. The water immiscible organic solvent,can be, but is not limited to, one or more of the following: chloroform,dichloromethane, and acyl acetate. The drug can be dissolved in, but isnot limited to, one or more of the following: acetone, ethanol,methanol, isopropyl alcohol, acetonitrile and Dimethyl sulfoxide (DMSO).

In some embodiments the polymer solution contains one or morepolycations or polycation containing polymers as described above. Thepolymer solution can contain a first amphiphilic polymer conjugatehaving a hydrophobic polymer block and a hydrophilic polymer block thatis or contains a polycation described above. In preferred embodimentsthe polymer solution contains one or more additional polymers oramphiphilic polymer conjugates. For example the polymer solution maycontain, in addition to the first amphiphilic polymer conjugate, one ormore hydrophobic polymers, hydrophilic polymers, lipids, amphiphilicpolymers, polymer-drug conjugates, or conjugates containing othertargeting moieties. By controlling the ratio of the first amphiphilicpolymer to the additional polymers or amphiphilic polymer conjugates,the density of the polycation can be controlled. The first amphiphilicpolymer may be present from 1% to 100% by weight of the polymers in thepolymer solution. For example, the first amphiphilic polymer can bepresent at 10%, 20%, 30%, 40%, 50%, or 60% by weight of the polymers inthe polymer solution.

An aqueous solution is then added into the resulting mixture solution toyield emulsion solution by emulsification. The emulsification techniquecan be, but not limited to, probe sonication or homogenization through ahomogenizer.

B. Nanoprecipitation Method

In another embodiment, a polycation containing nanoparticle is preparedusing nanoprecipitation methods or microfluidic devices. The polycationcontaining polymeric material, optionally mixed with a drug or drugcombinations in a water miscible organic solvent, and optionallycontaining additional polymers. The additional polymer can be, but isnot limited to, one or more of the following: PLA, PGA, PCL, theircopolymers, polyacrylates, the aforementioned PEGylated polymers. Thewater miscible organic solvent, can be, but is not limited to, one ormore of the following: acetone, ethanol, methanol, isopropyl alcohol,acetonitrile and Dimethyl sulfoxide (DMSO). The resulting mixturesolution is then added to a polymer non-solvent, such as an aqueoussolution, to yield nanoparticle solution. The plaque-targeted peptidesor fluorophores or drugs may be associated with the surface of,encapsulated within, surrounded by, and/or distributed throughout thepolymeric matrix of this inventive particle.

C. Microfluidics

Methods of making nanoparticles using microfluidics are known in theart. Suitable methods include those described in U.S. Patent ApplicationPublication No. 2010/0022680 A1 by Karnik et al. In general, themicrofluidic device comprises at least two channels that converge into amixing apparatus. The channels are typically formed by lithography,etching, embossing, or molding of a polymeric surface. A source of fluidis attached to each channel, and the application of pressure to thesource causes the flow of the fluid in the channel. The pressure may beapplied by a syringe, a pump, and/or gravity. The inlet streams ofsolutions with polymer, targeting moieties, lipids, drug, payload, etc.converge and mix, and the resulting mixture is combined with a polymernon-solvent solution to form the nanoparticles having the desired sizeand density of moieties on the surface. By varying the pressure and flowrate in the inlet channels and the nature and composition of the fluidsources nanoparticles can be produced having reproducible size andstructure.

VII. Methods of Using Polycation Containing Nanoparticles andFormulations Thereof

The formulations described herein can be used for the delivery of atherapeutic, prophylactic, or diagnostic agent to an individual orpatient in need thereof. Dosage regimens may be adjusted to provide theoptimum desired response (e.g., a therapeutic or prophylactic response).For example, a single bolus may be administered, several divided dosesmay be administered over time or the dose may be proportionally reducedor increased as indicated by the exigencies of the therapeuticsituation. It is especially advantageous to formulate enteralcompositions in dosage unit form for ease of administration anduniformity of dosage. Dosage unit form as used herein refers tophysically discrete units suited as unitary dosages for the mammaliansubjects to be treated; each unit containing a predetermined quantity ofactive compound calculated to produce the desired therapeutic

The present invention will be further understood by reference to thefollowing non-limiting examples.

EXAMPLES Materials and Methods

L-arginine, p-toluenesulfoninc acid monohydrate, succinyl chloride,adipoyl chloride, sebacoyl chloride, 1,2-ethanediol, 1,3-propanediol,1,4-butanediol, triethylamine, p-nitrophenol,3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT),N-Hydroxysuccinimide (NHS), and1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) were all purchasedfrom Sigma-Aldrich (St. Louis, Mo.) and used without furtherpurification. Organic solvents such as amethanol, toluene, ethylacetate, ethyl ether, 2-propanol, and dimethyl sulfoxide (DMSO) werepurchased from VWR Scientific (West Chester, Pa.) and were purified bystandard methods before use.

Two types of PLGAs with one carboxylic acid end group (PLGA-COOH) werepurchased from Lactel absorbable polymers and used without furtherpurification. High molecular weight PLGA1 (50/50, viscosity: 0.55-0.75dL/g) and low molecular weight PLGA2 (50/50, viscosity: 0.15-0.25 dL/g)have M_(n) around 45 kDa and 5.0 kDa, respectively, when measured by GPCwith THF solvent. AC2-26 peptide (AMVSEFLKQAWFIENEEQEYVQTVK) waspurchased from Tocris Biosciences. BSA, insulin, ovalbumin, andα-lactalbumin were all purchased from Sigma-Aldrich (St. Louis, Mo.) andused directly.

Hela, PC3, and A549 cell lines were obtained from American Type CultureCollection (ATCC, Manassas, Va.). All the cells were grown per therecommended ATCC protocols. The cell lines were used from passages 5 to12. Growth media was changed every 2 days. Cells were grown to 70%confluence before splitting, harvesting, or transfection. Dulbecco'smodified eagle medium (DMEM), penicillin-streptomycin (PS, 100 U/mL),trypsin-EDTA (TE, 0.5% trypsin, 5.3 mM EDTA tetra-sodium), fetal bovineserum (FBS) were obtained from Gibco BRL (Rockville, Md.). Other cellculture related chemicals, reagents, and buffers were purchased fromSigma-Aldrich (St. Louis, Mo.) unless otherwise specified.

Materials, nanoparticles, and complexes were characterized by variousstandard methods. For Fourier transform infrared (FTIR)characterization, the samples were ground into a powder and mixed withKBr at a sample/KBr ration of 1:10 (w/w). FTIR spectra were obtainedwith a PerkinElmer (Madison, Wis.) Nicolet Magana 560 FTIR spectrometerwith Omnic software for data acquisition and analysis. 1H-NMR spectrawere recorded on a Brukner AVANCED-400 NMR spectrometer. Deuteratedwater (D20-d2; Cambridge Isotope Laboratories, Andover, Mass.) withtetramethylsilane as an internal standard or denatured dimethylsulfoxide (DMSO-d6; Cambridge Isotope Laboratories, Andover, Mass.) wereused as the solvent. MestReNova software was used for data analysis. Themolecular weight of the polymers was measured by GPC, using THF or 0.1%(w/v) LiCl in DMAc solution as solvents. The polymers were prepared at aconcentration of 1 mg/mL (w/v) in solvent. The sample molecular weightswere determined from a standard curve generated from polystyrenestandards that were chromatographed under the same conditions as thesamples. The solubility of the polymers in common organic solvents atroom temperature was assessed using 1.0 mg/mL as a solubility criterion.The quantitative solubility of polymers in distilled water at roomtemperature was measured by adding distilled water drop by drop until aclear solution was obtained. The NP sizes and ζ-potentials were obtainedusing quasi-electric laser light scattering using a ZetaPALS dynamiclight scattering detector (15 mW laser, incident beam ¼ 676 nm;Brookhaven Instruments). Electron microscopy (EM) was performed at theHarvard Medical School EM facility on a Tecnai G2 Spirit BioTWIN EM.

Where appropriate, the data are presented as mean±standard deviationcalculated over at least three data points. JMP software (version 8.0,from SAS Company) was used for data analysis. Significant differencescompared to control groups were evaluated by unpaired Student's t-testor Dunnet test at p 0.05, and between more than two groups by Tukey'stest with or without one-way ANOVA analysis of variance.

Example 1. Synthesis of L-Arginine Polycation Polymers

A water-soluble L-arginine-based polycation (PC) library was developedaccording to a modified synthesis protocolof (Wu et al., Adv. Func.Mat., 2012, 22: 3815; Wu et al., J. Mat. Chem., 22: 18983 (2012). ThePCs were prepared via polycondensation between two monomers:di-p-nitorphenyl esters of dicarboxylic acid monomers (monomers I) andtetra-p-toluenesulfonic acid salts of bis (L-arginine), a, co-alkylenediesters (monomers II).

Di-p-nitrophenyl esters of dicarboxylic acids (monomers I) were preparedby reacting dicarboxylic acyl chloride varying in methylene length withp-nitrophenyl (Wu et al., J. Mat. Chem., 22: 18983 (2012)). Threemonomers were prepared: di-p-nitrophenyl succinate (NSu with x=2);di-p-nitrophenyl adipate (NA with x=4); and di-p-nitrophenyl sebacate(NS with x=8), wherein the ‘x’ indicates the number of methylene groupsin the diacid. For example, di-p-nitrophenyl adipate (NA) was preparedby the reaction of adipoyl chloride (0.15 mol) with p-nitrophenol (0.31mol) in acetone in the presence of triethylamine (0.32 mol). Thep-nitrophenol and triethylamine acetone solution (400 mL) was maintainedat 0° C. using an ice/water bath. Adipoyl chloride was diluted in 100 mLof cold acetone and added dropwise to the p-nitrophenol andtriethylamine acetone solution with stirring for 2 h at 0° C. andovernight at room temperature. The resulting di-p-nitrophenyl adipatewas precipitated in distilled water, washed completely, and then driedin vacuo at room temperature before final recrystallization in ethylacetate. The purification process was performed three times. The finalproduct was recovered as a brown colored crystal.

Tetra-p-toluenesulfonic acid salts of bis (L-arginine), α,ω-alkylenediesters (monomers II) were prepared according to Yamanouchi, et al.,Biomaterials 29:3269 (2008). The following is an example of a synthesisprotocol for tetra-p-toluenesulfonic acid salt of bis (L-arginine)butane diesters. L-arginine (0.04 mol) and 1,4-butanediol (0.02 mol)were directly mixed in a three neck round bottom flask with toluene (400mL, b.p. 110° C.) with the presence of p-toluenesulfonic acidmonohydrate (0.082 mol). The solid-liquid reaction mixture was heated to130° C. and reflux with stirring for 24 hr with 2.16 mL (0.12 mol) ofwater generate. The reaction mixture (viscous solid) was then cooled toroom temperature. Toluene was decanted. The resulting product wasfinally purified by dissolving the product in 2-propanol at 75° C. withstirring and then precipitating at 4° C. for three times. The idealprecipitation time is around 12h. 2-propanol was changed each time afterprecipitating and decanted afterwards, and the white sticky mass wasdried in vacuo. The final product was a white powder. Three monomers IIwere made: tetra-p-toluenesulfonic acid salt of bis (L-arginine) ethanediesters, Arg-2-S, (y=2); tetra-p-toluenesulfonic acid salt of bis(L-arginine) propane diesters, Arg-3-S(y=3); tetra-p-toluenesulfonicacid salt of bis (L-arginine) butane diesters, Arg-4-S(y=4); S indicatesthat the Arg diester monomer is in the p-toluenesulfonic acid salt form.The monomers are a white solid powder. The chemical structures of allthe monomers I and II were confirmed by ′HNMR.

The arginine based polycations (PCs) were prepared by solutionpolycondensation of the monomers I (NSu, NA and NS) and monomers II(Arg-2-S, Arg-3-S, and Arg-4-S) with a variety of combinations using amodified protocol. The molar ratio of monomers I to II was changed from1.0/1.0 to designed weight ratios so that PCs could be obtained withcontrollable end groups and molecular weight. Molar ratios of monomers Ito II was varied to be smaller than 1.0 so that the NH₂ end groups couldbe obtained. The specific monomer combinations and weight ratios and theresulting PCs are summarized in Table 1.

An example of the synthesis of the polycation from NS and Arg-2-S with amolar ratio of 9.0 to 10.0 via solution polycondensation is given here.Monomers NS (0.9 mmol) and Arg-2-S(1.0 mmol) in 2.0 mL of dry DMSO weremixed well by vortexing. The mixture solution was heated up to 70° C.with stirring to dissolve the monomers and obtain a uniformed mixturesolution. Triethylamine (0.31 mL, 2.2 mmol) was added drop by drop tothe mixture at 70° C. with vigorous stirring until the completedissolution of the monomers. The solution color turned yellow afterseveral minutes. The reaction vial was then kept for 48 hrs at 70° C. ina thermostat oven without stirring. The resulting solution wasprecipitated in cold ethyl acetate, decanted, dried, re-dissolved inmethanol and re-precipitate in cold ethyl acetate for furtherpurification. The purification was repeated 2 times before drying invacuo at room temperature. The final PCs are a yellow or pale yellowsolid powder. The chemical structures of all the PCs were confirmed by¹H NMR. The molecular weights of PCs with molar ratio(I/II) equal to9/10 were roughly around 9.0-10.0 kDa, while molecular weights of PCswith molar ratio(I/II) equal to 3/5 were roughly around 3.5-4.0 kDa.

The prepared PCs are strongly polar. All prepared PCs are soluble inbuffers, distilled water (>1.0 mg/mL) and polar organic solvents likeDMSO, DMF and methanol. They are insoluble in non-polar or weak polarorganic solvents like ethyl acetate, DCM, chloroform, THF and organicsolvents. For the aqueous solubility of PCs developed in this study, theeffect of x and y material parameters on PCs water solubility revealedthat both x and y had a major impact on the water solubility of PCs. Anincrease of x or y significantly reduced the water solubility due to theincreasing hydrophobicity. For example, PC3 (x=2 and y-3) has asolubility around 10 times of PC 15 (x=8 and y=3) (about 200 mg/mLversus 20 mg/mL).

TABLE 1 Summary of the PC library PC Name X Y Molar ratio (I/II) PCI 2 29/10 PC2 2 2 3/5  PC3 2 3 9/10 PC4 2 3 3/5  PC5 2 4 9/10 PC6 2 4 3/5 PC7 4 2 9/10 PC8 4 2 3/5  PC9 4 3 9/10 PC10 4 3 3/5  pen 4 4 9/10 PC12 44 3/5  PC13 8 2 9/10 PC14 8 2 3/5  PC15 8 3 9/10 PC16 8 3 3/5  PC17 8 49/10 PC18 8 4 3/5 

Example 2: Synthesis of Polycation Containing Block Copolymers

Di-block copolymers of PLGA-b-PC were prepared by coupling the carboxyterminal of PLGA and the amino functionality of PC via1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) andN-hydroxysuccinimide (NHS) activation methodology (FIG. 6).

The obtained PLGA-b-PC copolymers were pale-yellow or yellow solids withhigh yields (70-90%), depending on the PLGA-b-PC composition. Theprepared di-block copolymers of PLGA-b-PC were named PLGAy-PCx. Twotypes of PLGA-COOH with significantly different MWs were used: PLGA1(Mn=43.5 kDa) and PLGA2 (Mn=5.0 kDa). The chemical structures ofprepared PLGA-b-PC copolymers were confirmed by ¹HNMR. This exampleindicates that the percentage of PLGA-PC cationic moiety could bealtered by changing the PLGA MW, an important factor for NPfunctionality.

PLGA-PC polycations were prepared by conjugating NH2-PC-NH2 to PLGA-COOHvia the NHS/EDC chemistry route. The reaction conditions for thesynthesis PLGA-PC polycations were exemplified by the following exampleprotocol:

1. Dissolve 500 mg of PLGA-carboxylate (high molecular weight, around0.01 mmol) in 2.0 mL dichloromethane (DCM).

2. Dissolve NHS (6.0 mg, 0.05 mmol) and EDC (9.6 mg, 0.05 mmol) in 1.0mL DCM.

3. PLGA-carboxylate is converted into PLGA-NHS by adding the EDC/NHSsolution to a PLGA carboxylate solution with gentle stirring for 3hours.

4. PLGA-NHS is precipitated with 40 mL cold ethyl ether/methanol washingsolvent by centrifugation at 2,700×g for 10 min to remove residualEDC/NHS.

5. Repeat washing and centrifugation two times.

6. The PLGA-NHS pellet is dried under vacuum for 12 hours to removeresidual ether and methanol.

7. After drying under vacuum, PLGA-NHS (200 mg, 0.004 mmol) is dissolvedin DMSO (5.0 mL) followed by addition of PC3 with NH₂ end groups (120mg, around 0.012 mmol) and DIEA (15.0 mg, 0.012 mmol). The mixturesolution is incubated for 24 h at room temperature under gentlestirring.

8. Precipitate the resulting PLGA-6-PC block copolymer withether/methanol washing solvent and centrifuge to remove unreacted PC andother impurities.

9. Repeat washing and centrifugation two times.

10. Dry the purified PLGA-fr-PC polymer under vacuum. The final productsof PLGA-i-PCs are white or white-yellow powder or viscous solid. Theprepared PLGA-PCs are insoluble in buffers and distilled water and theorganic solvents like methanol, ethyl acetate, ACN, ethyl ether, butsoluble in polar organic solvents like DMSO and DMF. Some of them havelow solubility (a few mg/mL) in DCM, chloroform and THF, depending onthe copolymer composition. They should be stored at −20° C. for longterm storage. The polymer structure is confirmed by ¹HNMR.

Example 3: Characterization of PLGA-b-PC Nanoparticles

Materials and Methods

PLGA-b-PC copolymers could be fabricated into variable nanostructuresthrough different methods, including nanoprecipitation, single emulsion,and double emulsion. The nanoprecipitation method was chosen, becausethe resulting PLGA-PC NPs would have the desired core (PLGA)-shell (PC)structure with small size while still being simple, fast to manufacture,and reproducible.

Because of the insolubility of PLGA-PCs in many organic solvents, DMSOwas used as the organic solvent for the nanoprecipitation step. First,PLGA-6-PC (20 mg/mL) was dissolved in DMSO. Then the polymer solutionwas added dropwise to 19 volumes of stirring distilled water with orwithout surfactants giving a final polymer concentration of 1.0 mg/mL.The particle size and size distribution are measured by dynamic lightscattering at 25° C., with a scattering angle of 90°, and using a NPconcentration of approximately 0.1 to 0.5 mg/mL. The NP surface zetapotential is measured and recorded as the average of three measurements.Transition electron microscopy (TEM) was used to confirm the size andstructure of the NPs. A solution of NPs in distilled water (0.1-0.5mg/mL) was absorbed on grids and negatively stained for 15 seconds. Foreach sample, 5-6 grids are prepared and viewed. Images were normallytaken at 13-49,000*magnification.

The PLGA-PC NPs were characterized in terms of particle size, surfacecharge (zeta potential), and particle structure (surface morphology andshape) by a variety of methods. The particle size and surface charge ofPLGA-PC NPs are very important for the next step of the formulation andwill be discussed in detail below.

Results

The TEM images and DLS results show that the particle size of thePLGA-PC NP formed via nanoprecipitation were mainly in the range of20-80 nm, depending on the PLGA-PC composition. PLGA MW was thedominating factor for resulting NP size: low-MW PLGA2-based PLGA-PC NPswere mainly in the size range of 20-40 nm; while the high-MW PLGA1-basedPLGA-PC NPs were mainly in the size range of 40-80 nm. Compared to thecorresponding PLGA NPs, the PLGA-PC NPs were smaller. TEM imagesdemonstrated that the PLGA-PC NPs were spherical or egg shaped, whilethe surface morphology was fluffy due to the thick PC shell under drystate. The surface charges (zeta potential) of nanoprecipitated NPs werein the range of +15 to 50 my. For these systems, the surface charge ofNPs was not correlated with PLGA or PC structure or MW.

The cytotoxicity of PLGA-PC NPs was evaluated via an MTT assay. ThePLGA-PC NPs were not toxic to either Hela or PC3 cells in theconcentration range of 1.0 ng/mL to 200 μg/mL.

Stability tests of PLGA-PC NPs showed that all nanoprecipitated NPs werestable in PBS buffer or distilled water for weeks with the presence ofPVA, TWEEN®-80, lipid, or lipid-polyethylene glycol(PEG).

Example 4: Manufacture of PLGA-PC/BSA Nanoparticles

Although many strategies have been developed for loading NPs withproteins, serious challenges remain regarding easily and safely loadinga high quantity of proteins into NPs of reasonably small size. ThePLGA-PC NPs were designed with these goals in mind, and it is believedthat body charge density, not the surface charge, determines the proteinloading efficiency of a NP. In order to better utilize the electrostaticfield of the thick PC shell to strongly adsorb proteins and form new NPcomplexes with desired size and protein loading, a few formulationstrategies were tried until a very simple method with the lowestcontamination was chosen: direct mixing of aqueous solutions containingPLGA-PC NPs and proteins. Before the systematic study, a quickexperiment was carried out to verify this proof of concept by simplymixing random amounts of PLGA-PC NP solutions with BSA solutions.

After mixing there are some changes in terms of zeta potential, particlesize, and structure, depending on PLGA-PC type, weight ratio (WR) ofPLGA-PC to protein, and other formulation conditions. PLGA1-PC16 NP wasmixed with 2 wt % bovine serum albumin (BSA) in aqueous solution. Aftermixing, each PLGA-PC NP was loaded with some protein. Some NPsaggregated through bound proteins, but the structure of this complex wasrandom and irregular.

For the preparation of PLGA-PC/protein complex, freshly prepared BSAsolution (1-5 mg/mL) was quickly added to predetermined volumes offreshly prepared PLGA-PC NP distilled water solution (0.1¬0.5 mg/mL) ata stirring speed of 800-1200 rpm for 60 seconds.

For the preparation of PLGA-PC/protein/Lipid-PEG complex sphere orPLGA-PC/protein/lipid complex sphere, the Lipid-PEG or lipid aqueoussolutions freshly prepared then the solutions were quickly mixed withfreshly prepared PLGA-PC/protein complex sphere. Then concentrated PBSbuffer was added to obtain a final IX concentration of PBS.

Example 5: Characterization of PLGA-PC/BSA Nanoparticles

Materials and Methods

To investigate the relationships among protein loading efficiency,particle size, structure, and surface charge of the PLGA-PC NP/BSAcomplex, two types of PLGA-PC NPs were selected to systematicallyinvestigate the NP-protein interaction and the structure-functionrelationship. The two types of PLGA-PC NPs (PLGA1-PC16 and PLGA2-PC16)had very similar polymer structure: the PC blocks were identical, whilePLGA blocks had the same structure but significantly different MWs (43.5kDa and 5.0 kDa, respectively). Since the MW of PC16 is around 4.5 kDa,the PC composition of PLGA1-PC16 NP is about 9.4 wt %, while the PCcomposition of PLGA2-PC16 NP is about 47.4 wt %. Therefore, the twosystems have completely different PC composition percentage (a five-folddifference), making comparison straightforward. BSA was used as a modelprotein due to its suitable size (MW=66.5 kDa) and charge properties(isoelectric point=4.7).

For each PLGA-PC NP system, various PLGA-PC/BSA hybrid complexes wereformed by simply mixing aqueous solutions with a series of desiredweight ratios (“WRs”) of PLGA to BSA, ranging broadly from 5,000 to 2.

Results

FIGS. 8 and 9 show the particle size and zeta potential of newly formedPLGA-PC/BSA hybrid particles as a function of the WR of PLGA-PC NP toBSA. The zeta potential trend of FIGS. 8 and 9 can be divided into fourregions, depending on the PLGA-b-PC copolymer structure and WR ofPLGA-PC NP to protein. In the first region, as the WR of PLGA-PC NP toprotein decreased from 5,000 to a few hundred, the zeta potential of thecomplex particles decreased, indicating that if more proteins were mixedwith PLGA-PC NPs, more of the positively charged surface of the PLGA-PCNP was surrounded or covered by negatively charged proteins viaelectrostatic interaction. In the second region, with more proteinsadded (WR from a few hundred to a few tens), almost all of the PLGA-PCNP surface was finally covered with proteins and the zeta potentialchanged from positive to zero or slightly negative. At this stage, thecorresponding WR to the 0 my zeta potential is determined by thePLGA-b-PC copolymer composition (PC percentage). For the third region, afurther decrease of the WR of PLGA-PC NP to protein continued todecrease the zeta potential of the complexed particle to around −30 my.For the fourth (last) region, the zeta potential continued to decreaseor plateaued at a value slightly more negative than the zeta potentialof pure BSA.

The particle size trend in FIGS. 8 and 9 can also be divided into theexact same four regions. In the first region, as the WR of PLGA-PC toBSA decreased, the size of the complex particle slightly and steadilyincreased, suggesting that as more protein was added into the PLGA-PC NPsolutions, the PLGA-PC NPs began to interact with or adsorb moreproteins on their surface. In the second region, as the WR of PLGA-PC NPto protein decreased further, the particle size of PLGA-PC NP/proteincomplexes significantly increased beyond the expected size range,indicating some form of aggregation. For the largest particle sizeobtained in this region, the corresponding zeta potential was aroundzero, which is reasonable since NPs with neutral surface charge tend tobe very unstable. After the second region, however, a continuingdecrease of WR in a narrow range (third region) immediately resulted ina significant reduction of complex particle size. This phenomenonsuggests that the particle may be in a stable state within this narrowWR range and is likely the optimal formulation. The small particle sizehad a corresponding zeta potential of approximately −20 mv, whichconfirmed its relatively stable state. In this region, the PLGA2-PCsystem had loaded protein in the range of 15-30 wt % with encapsulationefficiency over 95%. However, for the PLGA1-PC system, the correspondingprotein loading was in the range of 2-3 wt % due to the low PC density.In the fourth (last) region, the continuously decreasing WR causedsignificant particle size increases, indicating aggregation. Thus, atvery high BSA concentrations, stable complexes were unable to form, anda large portion of BSA remained free.

These results show that for each type of PLGA-PC NP, the maximumeffective loading efficiency was achieved at a small particle size witha zeta potential range of −10 to −30 mv, in a narrow WR range of PLGA-PCto BSA. FIGS. 8 and 9 show the same trend for both size and zetapotential, but have different corresponding WR windows for the specificsmall particle size, suggesting that this is a function of polymerstructure. These relationships also exist for other PLGA-PC NPs.

In the third region of the PLGA2-PC system the complexed particles hadsmall sizes but maintained significant protein loading. TEM was used tostudy the complexed particle structure in this region for the PLGA2-PCsystem. To acquire better image quality and resolve more details, theformulation protocol was slightly modified so that larger NPs could beobtained without affecting structure. PLGA2-PC/BSA NPs with relativelylarge size at a WR of 4 were obtained after simple mixing. The structureand surface morphology of the complexed NPs were different from the purePLGA-PC NPs. Based on the NP size and protein loading, it was predictedthat multiple PLGA-PC NPs were contained in a single, complexed NP.Through TEM, the inner structure of complexes was examined, confirmingthat there were multiple PLGA-PC NPs inside, acting as the nucleus foreach complexed NP.

For the specific PLGA2-PC/Protein nanospheres formed in the thirdregion, the unmodified, complexed nanospheres were found to be unstablein buffered solutions. To improve stability, a variety of strategieswere tested. It was found that lipid and lipid-PEG both effectivelystabilized these nanospheres in buffer. For example,1,2-distearoylsn-glycero-3-phosphoethanolamine-N-methoxy (polyethyleneglycol) (DSPE-PEGm) stabilized the PLGA2-PC/Protein nanospheres inbuffer, additionally increasing the size by around 50 nm (while stillkeeping it below 200 nm) with only a 10 wt % decrease in overall proteinloading.

Example 6: BSA Loading and Release from PLGA-PC/BSA Nanoparticles

Materials and Methods

The release profile of the PLGA2-PC/protein nanosphere coated withDSPE-PEGm nanospheres in PBS buffer was studied.

BCA assay was used to measure the loaded and released protein in thisreport. All the steps are exactly following the manufacturer's protocol.A serial dilution of pure protein solutions with predeterminedconcentrations were used to make standard curve every time. For themeasurement of protein loading and release, since the PC component ofPLGA-PC NPs has a lot of amino acids and will affect the BCA results,the supernatant solution was collected and the inside free unloadedproteins were analyzed via BCA assay.

Results

As shown in FIG. 10, some burst release (around 20 wt %) was observedafter the addition of buffers, with fast release occurring over thefirst 1-2 days, especially in the initial hours. After a few hours,release of BSA was sustained and steady for at least three weeks.

FIG. 11 is a bar graph depicting the dependence of the zeta potential(mV) on the ratio (w/w) of PLGA-b-PEG to PLGA-b-PC. The PEG is 3.4K.

FIG. 12 is a bar graph depicting the dependence of the zeta potential(mV) on the ratio (w/w) of PLGA-b-PEG to PLGA-b-PC. The PEG is 2K.

FIG. 13 is a bar graph depicting the dependence of the particle size(nm) from dynamic light scattering on the ratio (w/w) of PLGA-b-PEG toPLGA-b-PC. The PEG is 3.4K. FIG. 14 is a bar graph depicting thedependence of the particle size (nm) from dynamic light scattering onthe ratio (w/w) of PLGA-b-PEG to PLGA-b-PC. The PEG is 2K.

Example 7: PLGA-PC Loading of Other Proteins/Peptides

Materials and Methods

Besides BSA, the interaction between PLGA-PC NPs and other negativelycharged proteins/peptides was also evaluated using ovalbumin,α-lactalbumin, insulin, and Ac2-26 peptide as models, with MWs around45.0, 14.0, 6.0, and 3.0 kDa, respectively.

Results

FIG. 15 is a graph of the cumulative insulin release (%) as a functionof time (days) for PLGA-PC/insulin nanoparticles prepared bynanoprecipitation.

FIG. 16 is a graph of the cumulative insulin release (%) as a functionof time (days) for PLGA-PC/insulin nanoparticles prepared by doubleemulsion.

Release appears to be faster in the nanoparticles made by doubleemulsion than by nanoprecipitation.

Results and relationships were similar to those found above. It wasconfirmed that the MWs of proteins/peptides did not significantly affectinteractions between PLGA-PC NPs and proteins. Additionally, multipletypes of negatively charged proteins could be loaded simultaneouslywithout making obvious sacrifices in loading efficiency.

Example 8: Cytotoxicity of PLGA-PC and PLGA-PC/Protein/Lipid-PEG

Materials and Methods

The cytotoxicity of PLGA-PC and PLGA-PC/Protein/Lipid-PEG nanoparticleswas evaluated by the MTT assay. An increase in cell number (cellproliferation) results in an increase in the amount of MTT formazanproduction and hence an increase in UV absorbance at the 570 nmwavelength. Two types of cells, Hela and PC3, were used for the MTTassay. The cultured cells were seeded at an appropriate cell densityconcentration (3,000 cells/well) in 96-well plates and incubatedovernight in a 5% CO₂ incubator at 37° C. The cells were then treatedwith various NP solutions for 4 h. PLGA-PC NP solutions were stabilizedwith 1.0 wt % polyvinylalcohol (“PVA”) or TWEEN®-80. The mixture ofmedia and NPs was removed and complete DMEM was then added into eachwell for 44 h incubation (total time, 48 h). The cells treated withnormal cell culture media only were used as the negative control (NC).After 48 h incubation (total treatment time) of the treated cells at 37°C. and 5% CO₂, 15 μL of MTT solution (5 mg/mL) was added to each well,followed by 4 h incubation at 37° C., 5% CO₂. Then the cell culturemedium was carefully removed and 150 μL of acidic isopropyl alcohol(with 0.1 M HCl) was added to dissolve the formed formazan crystal. ODwas measured at 570 nm (subtract background reading at 690 nm) using aVersaMax Tunable Microplate reader. The cell viability was expressed asthe percentage of the blank negative control. Triplicates were used ineach experiment.

Results

The MTT data clearly demonstrated that, after 4 h treatment, all thenanoparticle samples showed the same as or close to the blank control,i.e., very little cytotoxicity to the cells tested even at a largedosage such as 1 mg/mL.

Example 9: Cellular Uptake of PLGA-PC/BSA/Lipid-PEG Particles

Materials and Methods

BSA proteins were labelled with fluorescent dyeRhodamine-B-Isothiocyanate (RITC) and purified according tomanufacturer's protocol. The NPs of PLGA-PC/fluorescence BSA/Lipid-PEG(20 wt % BSA) were fabricated following the above protocol. A549 cellswere used for this cellular uptake evaluation. The cultured cells wereseeded at an appropriate cell density concentration (3,000 cells/well)in 96-well plates and incubated overnight in a 5% CO₂ incubator at 37°C. The cells were then treated with pure RITC labeled BSA (2.0 μg/mL) orPLGA-PC/fluorescence BSA/Lipid-PEG NP solution (10.0 μg/mL) for 4 h. AZeiss AXIOVERT® 200 fluorescence/live cell imaging microscope was usedto record the images.

Results

The results indicated that after four hours, large numbers of NPsentered the cells, and the loaded protein began to be released in asustained fashion.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of skill in the artto which the disclosed invention belongs. Publications cited herein andthe materials for which they are cited are specifically incorporated byreference. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific embodiments of the invention described herein. Suchequivalents are intended to be encompassed by the following claims.

1-25. (canceled)
 26. A method of providing sustained delivery of atherapeutic, prophylactic or diagnostic agent comprising administeringto an individual in need thereof a population of non-aggregatedparticles comprising: (a) one or more cationic polymer cores comprisinga block copolymer comprising a polycation block and a biodegradablepolymer block; and (b) a layer of anionic therapeutic, prophylactic ordiagnostic active agent encapsulating the one or more cationic polymercores, wherein the particle has a zeta potential between −10 mV and −30mV.
 27. The method of claim 26, wherein the one or more cationic polymercores has a diameter between 10 nm and 200 nm.
 28. The method of claim26, wherein the particle is a multi-core shell nanoparticle and thenanoparticle comprises more than one cationic particle core.
 29. Themethod of claim 26, wherein the particle has a diameter of between 10 nmand 1,000 nm.
 30. The method of claim 26, wherein the particle comprisesa protective layer and the anionic active agents are dispersed betweenthe protective layer and the one or more cationic particle cores. 31.The method of claim 30, wherein the protective layer is selected fromthe group consisting of lipid monolayers, lipid bilayers, biodegradablepolymer layers, polymer-lipid conjugate layers, and combinationsthereof.
 32. The method of claim 26, wherein the cationic particle corecomprises a second polymer comprising the biodegradable polymer butwithout the polycation block.
 33. The method of claim 26, wherein thebiodegradable polymer is selected from the group consisting ofpoly(lactic acid), poly(glycolic acid), and poly (lactic-co-glycolicacid).
 34. The method of claim 26, wherein the polycation blockcomprises a polymer comprising dicarboxylic acid ester units and unitsof (α-amino acid)-α,ω-alkylene diester units.
 35. The method of claim34, wherein the polycation block comprises units having the structure

wherein R₁ is selected from the group consisting of linear and branchedalkyl and substituted alkyl, alkenyl, or alkylene oxide groupscontaining from 2 to 20 carbon atoms; wherein R₂ is selected from thegroup consisting of aliphatic amines, cycloaliphatic amines,heterocyclic amines, and aromatic amines containing from 1 to 12 carbonatoms; and wherein n is an integer between 1 and 1,000.
 36. The methodof claim 35, wherein one or both R₂ is the side chain of a cationicamino acid selected from the group consisting of lysine, arginine,histidine, homolysine, ornithine, diaminobutyric acid, diaminopimelicacid, diaminopropionic acid, homoarginine, trimethyllysine,trimethylornithine, 4-aminopiperidine-4-carboxylic acid,4-amino-1-carbamimidoylpiperidine-4-carboxylic acid and4-guanidinophenylalanine.
 37. The method of claim 26, wherein one ormore of the cationic polymer cores comprise an inorganic particle andthe cationic polymer block is on the surface of the inorganic particle.38. The method of claim 37, wherein the inorganic particle comprises aparticle selected from the group consisting of gold particles, ironoxide particles, and silica particles.
 39. The method of claim 26,wherein the therapeutic or prophylactic agent is a protein.
 40. Themethod of claim 26, wherein the therapeutic or prophylactic agent is anucleic acid molecule.
 41. The method of claim 26, wherein the particlesare administered parenterally, enterally, pulmonarily, or topically.